Shipman et al - Intro to Physical Science 15/e

1. 2/3 points | Previous Answers ShipPS15 2.2.EQL.001. My Notes

[Question 1 is an engaging Quick Lesson animation video on speed and velocity, complete with text transcript. Students are guided through a concept and then asked as series of multiple-choice questions to gauge their comprehension. Quick Lessons are available for physics content.]

Watch the video below, then answer the questions that follow it.

(a)

In the video, you saw a car traveling along a road from a starting line to a finish line. The finish line was 150 m away from the starting line (along a straight line). Which of the following would best describe the 150 m? (Choose one.)

The distance the car traveled from the starting line to finish line was 150 m. The average speed of the car was 150 m. The average velocity of the car was 150 m. correct

The displacement (magnitude) from the starting line to finish line was 150 m.

✓ Correct. The straight line distance is the magnitude of the displacement vector.

(b)

Which of the following is the best way to determine the average speed of the car over its journey from the start to finish line?

Divide the 150 m straight-line distance by the total time from start to finish. Divide the length of a small segment of the car's path by the short time it takes to travel that segment. Divide the 200 m distance by the short time it takes to travel a small segment of the car's path. correct

Divide the 200 m distance by the total time from start to finish.

⨯ This is incorrect, as it is mixing ideas from average and instantaneous speed. What is the difference between the two? Review the video if necessary.

(c)

Which of the following statements about the instantaneous velocity of the car at some point on the path are true? (Select all that apply.)

The instantaneous velocity at a point can be approximated by finding the displacement near that point over a short time interval, and dividing it by that time interval. correct

The instantaneous velocity points in the direction of the car's motion at that point. correct

The magnitude of instantaneous velocity is the same as the instantaneous speed. The instantaneous velocity is a scalar quantity.

✓ Correct. The only false statement here is that instantaneous velocity is a scalar. It's actually a vector quantity.

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2. 4/9 points | Previous Answers ShipPS15 3.2.DWB.001. My Notes

In this section, we'll begin to discuss how the motion of objects is affected by the forces that act on them. Our first step will be to understand the concept of NewtonIsaac Newton (1643-1727) was an English mathematician and physicist who famously discovered the laws of motion and gravitation, and is widely regarded as one of the most influential scientists of all time.'s first law.

Carefully watch the video below, which introduces Newton's first law.

Part 1 of 4

GalileoGalileo Galilei (1564-1642) was an Italian scientist who made early, foundational contributions to the study of motion and to astronomy, and famously championed the idea that the Earth revolved around the Sun.'s reasoning led him to believe that a ball rolled down an inclined plane would continue moving indefinitely so long as which of the following is true?

The surface was perfectly smooth. The ball was small enough. The inclined plane was very steep.

Newton's first law states what?

An unbalanced force on an object is required for it to move at a constant velocity. correct

An unbalanced force on an object causes an object's velocity to change. An unbalanced force on an object is required to change an object's speed, but not required to change an object's direction.

Part 3 of 4

Here are a few more important points to keep in mind when thinking about Newton's first law.

Remember that an "unbalanced" force simply means a non-zero net force. If an object moves at constant velocity, there may be many forces acting on it, but the vector sum of all of the forces must be zero. A common example might be pushing a heavy box across a carpeted floor. You might exert a force to push the box forward, but the floor exerts a frictional force of the same magnitude in the opposite direction. The net force on the box is zero, and the box moves at constant velocity. The constant presence of friction in the world is one reason why Newton's first law can be difficult to understand.

Note that the law also refers to an externala force on an object or system of interest that is caused by something outside of that object or system, unbalanced force. "External" in this case simply means that the force on the object is due to another object (or objects). It is possible for particles that comprise objects or systems to exert forces on each other. These forces are "internala force that one particle or object within a particular system exerts on another particle or object within that same system" to the object. But as we'll see when we study Newton's third law and momentum, internal forces have no effect on the "average," overall motion of a multi-particle system.

The diagrams, labeled (i) to (iv), below show different objects of equal masses that are acted on by one or more forces. In the diagrams below, each force vector labeled

F

has the same magnitude. (The one labeled

2F

then has twice the magnitude of the others.)

(i) Two vectors both labeled F extend from a point in the center. One vector points to horizontally to the left and the second vector points to the right. Both vectors are of the same length.

(ii) Two vectors both labeled F extend from a point in the center. One vector points horizontally to the left and the second vector points down and to the right making an angle of 135 degrees with the first vector. Both vectors are of the same length.

(iii) Two vectors both labeled F extend from a point in the center. One vector points to horizontally to the left and the second vector points down. Both vectors are of the same length.

(iv) Two vectors labeled F and 2 F extend from a point in the center. F points horizontally to the left and the 2 F points to the right. 2 F is twice as long as F.

Which of the four objects shown has a net zero force acting on it?

(i) (ii) (iii) (iv)

✓ Correct. The two forces on this object have the same magnitude, but opposite directions. The net force is therefore zero.

Which object has a constant velocity?

(i) (ii) (iii) (iv)

✓ Correct. Because the net force is zero, by Newton's first law, the object's velocity will not change.

Part 4 of 4

Newton's first law states that an unbalanced force will change an object's velocity, but the extent to which the velocity changes depends on a property of the object called massMass is a measure of an object's inertia—its resistance to undergoing acceleration. In the SI system, it is measured in kilograms.. Below, we'll introduce the ideas of mass and inertia, which will become more important later, when we study Newton's second law.

Galileo was the first to notice a property called inertiaInertia is the tendency of an object at rest to stay at rest, or an object moving at a constant speed in a straight line to remain so. In other words, the tendency of objects to "resist" changes in motion, or accelerations.. Inertia is the natural tendency of an object to remain at rest, or to remain in motion at a constant speed in a straight line. Newton's first law, then, essentially says that all objects have some amount of inertia.

Mass is essentially synonymous with inertia—it is a quantitative measurement of the amount of inertia. Mass can be thought of as the amount an object "resists" a change in motion, given the same applied force.

Most of us have an intuitive feel for mass—a more massive object feels heavier. We need to be careful, though, as mass and weight, as we'll later see, are not the same. Weightthe gravitational force acting on an object is a measure of the gravitational force on an object, which is proportional to mass. The weight of an object on Earth is less than its weight on, for example, the Moon, since the Moon exerts less gravitational force. But the mass of the object is the same no matter where it is—mass is an intrinsic property of an object.

You can get a sense for how mass affects motion by imagining pushing a someone on a swing. Push a small child sitting at rest on a swing, and you find you can easily change the child's velocity. Now imagine an adult sitting on the swing instead. The adult is much more massive than the small child. So, pushing the adult from rest would require much more force to cause the same change in velocity (given you push both for about the same amount of time).

In the SI system, mass is measured in units of kilograms, or kg. An object with a mass of 1 kg weighs (on Earth) about 2.2 pounds, or about 9.8 newtons.

Imagine two identical grocery carts, each with wheels that roll smoothly. One cart is empty. The other is filled with groceries, which have a total mass of 10 kg. Which would be more difficult to push from rest to a speed of 2 m/s? (That is, which would require greater force, or a longer time to push, to see the same change in motion?)

the empty cart correct

the filled cart both would require the same effort

✓ Correct. The filled cart has more mass, therefore more inertia, and therefore more "resistant" to a change in speed.

Once both carts are moving at 2 m/s, they each roll with almost no friction. Which of the following is true?

The filled cart requires a force to keep moving, while the empty cart continues to move at the same speed. The empty cart requires a force to keep moving, while the filled cart continues to move at the same speed. Both carts will require the same force to keep moving, otherwise they will both nearly immediately come to a stop. correct

Both carts continue to roll at about the same speed. No applied force is necessary.

✓ Correct. Once they are both moving at a constant velocity, Newton's first law says they continue at a constant velocity, if there is no unbalanced force. Mass and inertia are only relevant to changing the velocity.

You have now completed the Workbook lesson.

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3. 3/11 points | Previous Answers ShipPS15 3.6.DWB.001. My Notes

[Question 3 is another part of the new Digital Workbook, this time focusing on Buoyancy and Archimedes' Principle with an interactive simulation in part 4 that shows two forces acting upon a block's center of mass.]

*Source*: Shutterstock.com
A photograph of an aircraft carrier.

How is it that some of the heaviest things ever built can float on water? With the help of buoyancy and Archimedes' principle, that's how!

In this lesson, we'll first explore the concept of density (how loosely or tightly matter is packed into a given volume).

We'll then learn why any floating or immersed object must experience an upward force called buoyancythe tendency for an object to rise when immersed in a fluid with a greater density than that of the object.

Finally, we'll encounter Archimedes' principleIf an object is at least partly submerged in a fluid, it will feel an upward buoyant force. The strength of that force equals the weight of the displaced fluid. and apply it to subjects like icebergs and scuba diving.

Part 1 of 4 - Density

Most people have seen that a chunk of Styrofoam will float on water, while a chunk of iron will sink. Ask them why, and they may say "the iron's heavier." But a 2-pound chunk of Styrofoam will float on water, while a quarter-pound bar magnet will sink. Break the Styrofoam in half, and each half will still float; break the magnet in half, and each half will still sink.

All of this suggests that some property other than mass must determine whether a substance will float or sink in water—a property that stays the same even if you break a piece of it in half! That property is densitythe amount of mass that occupies a unit of volume. Defined as the ratio of mass to volume, density tells us how tightly packed matter is within a material.

Density is an intrinsic property of any material, such as liquid water or Styrofoam. It does not depend on how much of the material you happen to have: whether you have a 2-pound chunk of Styrofoam or a 10-pound chunk of Styrofoam, the density of the Styrofoam remains the same.

Density is easily confused with mass and weight. Here's one way to keep them straight: two liters of tap water will have the same density as one liter, but twice the volume, twice the mass, and twice the weight.

Suppose you have a small cup of water and your friend holds a much larger cup (both are full). Both cups are paper, so you can ignore the mass and weight of the cup itself. Which one of these statements is true?

The two servings of water have different masses but the same density. The two servings of water have the same mass and the same density. The two servings of water have the same mass but different densities. The two servings of water have different masses and different densities.

Part 2 of 4 - To Float or Sink

Density is the property that determines whether an object will rise or sink in a particular fluidFluid is a state of matter where atoms or molecules easily flow around each other and does not assume a particular shape unless held in a rigid container. It comprises both liquids and gases (with liquids generally being much more dense and much less compressible than gases).. In short, an object will sink into a fluid if the object is denser than the fluid. Conversely, the object will rise if it is less dense than the fluid.

The density of a sample (such as a cupful of water) or object (such as a wooden block) can be calculated if you know (or measure) its massMass is a measure of an object's inertia—its resistance to undergoing acceleration. In the SI system, it is measured in kilograms. and volumeVolume is a measure of how much space is taken up by an object, or by a sample of a substance. English units include the fluid ounce, the cubic foot, and the gallon. Metric units include the cubic centimeter, the liter, and the cubic meter.. The formula is

density =

mass

volume

,

or, in symbols,

ρ =

m

V

,

where the lowercase Greek letter rho (ρ) stands for density.

The SI unit for density is kilograms per cubic meter, or kg/m³.

Here are some typical densities of everyday substances.

	fresh water	wood (pine)	air (normal)	iron
density (kg/m³)	1,000	500	1.3	8,000

A cubic meter is roughly the volume of the box that a clothes dryer or dishwasher is shipped within. If you could fill such a box with water, you'd have a tonA ton is a unit of mass or weight, equivalent in the metric system to 1,000 kg and in the British system to 2,000 pounds. (One British ton weighs slightly less than a metric ton.) of water on hand.

Mineral oil has a density of 850 kg/m³. Which is denser, water or mineral oil?

water mineral oil

✓ Correct! At 1,000 kg per cubic meter, water is denser than mineral oil.

A fluid can be liquid (like water) or gas (like the atmosphere). When liquids are involved, an object will float on the surface if less dense than the liquid.

Imagine that you had a book-sized chunk of Styrofoam whose density is 50 kg per cubic meter. At that density, it will float on the surface of water.

Now suppose that you could crush it so that it only took up half as much space as before. How would that affect its volume?

Its volume would halve. Its volume would not change. Its volume would double.

⨯ Incorrect. Volume is proportional to the amount of space that an object or sample occupies.

How would crushing the sample affect its density?

Its density would not change. Its density would halve. correct

Its density would double.

⨯ Incorrect. Density is inversely proportional to volume.

Would the Styrofoam piece float on water or sink into water, after being crushed as described above, and why?

It would float because it has the same mass as before. correct

It would float because its density would remain less than that of water. It would sink because its density would become greater than that of water.

⨯ Incorrect. Whether the piece will float or sink depends on how its density compares to that of water.

Part 3 of 4 - The Buoyant Force

When floating motionless above a coral reef, a scuba diver is subject to two forces that cancel each other out. One is her weight, the downward force of the Earth's gravity, which operates just as well in the water as on solid ground. The other is the buoyant forceBuoyant force is the upward force experienced by an object that is immersed in, or floating upon, a denser fluid. The strength of the force is given by Archimedes' Principle and equals the weight of the amount of fluid that the object has displaced., which pushes her upward.

The strength of the buoyant force is given by ArchimedesGreek scientist (3rd Century BCE) famous for many discoveries and inventions in math, physics, and engineering' principle.

If an object is at least partly submerged in a fluid, it will feel an upward buoyant force. The strength of that force equals the weight of the displaced fluid.

How much does the displaced fluid weigh? That depends on three things.

the amount of space that the submerged object takes up below the surface of the fluid (the volume, V)
the density of the fluid (ρ_fl)
the acceleration due to gravity (g)

The product of these factors tells us how strong the buoyant force is.

buoyant force = immersed volume ✕ fluid density ✕ g

or, in symbols,

buoyant force = Vρ_flg.

Strictly speaking, a buoyant force acts upon us when we are walking around in air—after all, the atmosphere is a fluid! Why don't we feel a floating sensation when going about our daily lives?

We've gotten used to this force. correct

The air has very low density.

A blimp or hot-air balloon, by contrast, can be lifted off the ground and into the atmosphere by buoyant forces. How is this possible, if air is so "thin"?

The blimp or hot-air balloon shoots gas downward, like a rocket. correct

The average density of the blimp or balloon is even lower than the air's.

Imagine that you have two identical wooden blocks, a jar of water, and a jar of cooking oil. You hold one block under the surface of water, and the other under the surface of the oil. The water has a density of 1,000 kg/m³, while a cubic meter of oil would contain "only" about 900 kg.

How would the buoyant forces on the blocks compare?

The block in oil would feel a greater buoyant force than the block in water. The blocks would feel equal buoyant forces. correct

The block in water would feel a greater buoyant force than the block in oil.

Below there is a simulated container with a block and a fluid. Each has a uniform density that can be adjusted with a slider or number-entry box. The units are grams per cubic centimeter (g/cm³). How does that compare to kilograms per cubic meter? Easy! Just equate the density of water in the two systems.

1 g/cm³ = 1,000 kg/m³ and this implies 1 kg/m³ = 0.001 g/cm³

In any case, all you need to know for now is that water has a density of roughly 1.0 g/cm³.

The simulation shows two forces that act upon the block's center of mass, marked by an x.

B	=	buoyant force
F_g	=	force of gravity (a.k.a. weight)

Experiment with different slider settings, and you'll notice that the block's motion is governed by the net force—the degree to which one of these forces "wins" (and its direction).

Newton's First Law tells us that a stationary block will begin to move unless the net force is zero (that is, unless the forces balance each other out). The exception is at the bottom of the container, because a third force (the normal force) pushes up on the block but isn't shown.

Set the fluid density to 1.0 g/cm³.

Set the block density to 0.9 g/cm³.

Allow the block to stabilize if it has moved.

Knowing that 0.9 equals 90%, what can you say about the percentage of the block that is submerged (given at the lower-right corner of the simulation)?

The submerged percentage of the block is equivalent to its density in g/cm³. The submerged percentage of the block is equivalent to its density relative to water. correct

Both of the above statements are true.

⨯ Half right! Recall that the density of water is 1.0 gram per cubic centimeter.

Now set the fluid density to 0.9 g/cm³, which matches some kinds of cooking oil. What percentage of the block is now underwater?

100

✓ Correct! The fluid and block now have equal densities, and the simulation indicates that the block is 100% submerged, as expected. %

Return the fluid density to 1.0 g/cm³ while leaving the block density at 0.9 g/cm³.

At temperatures just below freezing, water ice has a density of about 0.9 g/cm³. What does this imply about icebergs floating at sea? (Note: seawater is only 2 to 3 percent denser than fresh water, so you can ignore any difference for now.)

Nearly all of an iceberg's bulk is under water. Most of an iceberg's bulk is above the water line. Icebergs are about half above, half below the water line.

✓ Correct. As we saw in the simulation, the density of the block, relative to the fluid, gives the percentage of the block that remains submerged. Since ice is about 90% of the density of liquid water, about 90% of the iceberg is under water.

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4. 1/1 points | Previous Answers ShipPS15 3.3.E.003. My Notes

[Question 4 is a quantitative exercise with algorithmic variables in red.]

Determine the net force (in N) necessary to give an object with a mass of 2.90 kg an acceleration of 5.10 m/s².

14.8

N

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5. 0/1 points | Previous Answers ShipPS15 3.7.E.023. My Notes

[Question 5 is a quantitative exercise with algorithmic variables in red.]

Two ice skaters stand together as illustrated in Figure (a) below. They "push off" and travel directly away from each other, the boy with a velocity of v = 0.680 m/s to the left. If the boy weighs 750 N and the girl weighs 468 N, what is the girl's velocity (in m/s) after they push off? (Consider the ice to be frictionless.)

Two ice skaters, a boy on the left and a girl on the right, face each other in figures a and b, which depict, respectively, before and after pushing off from each other.

**Before:** The two ice skaters face each other with the palms of their hands facing towards each other and touching the other person's palms.

**After:** The two ice skaters have pushed off and now have their arms outstretched facing each other. A left-pointing arrow above the left skater is labeled "v". A right-pointing arrow above the right skater is labeled "?".

1.09

m/s

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6. 2/2 points | Previous Answers ShipPS15 3.5.E.013. My Notes

[Question 6 is a numeric question that involves the math skill of reasoning with proportions.]

How would the force of gravity between two masses be affected if the separation distance between them were the following? (Assume F₂ represents the new force and F₁ represents the original force.)

(a)

triple the original distance

F₂

F₁

=

0.111

(b)

one-third the original distance

F₂

F₁

=

9

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7. 1/1 points | Previous Answers ShipPS15 3.2.MC.002. My Notes

[Question 7 is a qualitative multiple-choice question.]

What is a possible state of an object in the absence of a net force?

at rest zero acceleration constant speed correct

all of these

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8. 1/1 points | Previous Answers ShipPS15 3.7.MC.014. My Notes

[Question 8 is a qualitative multiple-choice question.]

A change in linear momentum requires which of the following?

a change in velocity an acceleration an unbalanced force correct

all of these

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9. 1/1 points | Previous Answers ShipPS15 20.AYK.001. My Notes

[Question 9 is a qualitative, multiple-select "Applying Your Knowledge" question from the text.]

Why do household barometers often have descriptive adjectives such as rain and fair on their faces, along with the direct pressure readings? (Select all that apply.)

Fair weather is associated with high pressure. The descriptive adjectives are present to give a general idea of the proper range of weather. Fair weather is associated with low pressure. Bad weather is associated with high pressure. correct

Bad weather is associated with low pressure.

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10. 3/6 points | Previous Answers ShipPS15 13.1.E.001. My Notes

[Question 10 is a multipart question asking students to balance several equations. It uses WebAssign's chemPad tool that enables students to input responses that are automatically displayed in correct chemical notation. The chemPad tool includes a row of buttons at the top, a formatted display area in the middle, and a text entry box at the bottom. Click here to learn more.]

Balance these chemical equations. (Use the lowest possible whole number coefficients.)

(a) K + Br₂ → KBr

chemPad

Help

→ K + Br₂ → 2KBr

(b) Ga + H₂SO₄ → Ga₂(SO₄)₃ + H₂

chemPad

Help

2Ga + 3H₂SO₄ → Ga₂(SO₄)₃ + 3H₂

(c) HgO → Hg + O₂

chemPad

Help

2 HgO → 2 Hg + O₂

(d) S₈ + O₂ → SO₃

chemPad

Help

S₈ + 12O₂ → 8SO₃

(e) Fe + O₂ → FeO

chemPad

Help

(f) C₆H₅OH + O₂ → CO₂ + H₂O

chemPad

Help

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Shipman et al - Intro to Physical Science 15/e (Homework)

Current Score : 18 / 36

Due : Monday, January 28, 2030 00:00 EST

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Shipman et al - Intro to Physical Science 15/e (Homework)

Current Score : 18 / 36

Due : Monday, January 28, 2030 00:00 EST

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