Physics CH 7-10
Video: Velocity During Projectile Motion Part A Predict how the horizontal component of the velocity will change with time after the projectile is fired. Part B Predict how the vertical component of the velocity will change with time after the projectile is fired.
A- It stays constant. B- It first decreases to zero and then increases in the opposite direction.
Multiple Choice Question 10.38 Part A The radial velocity of an Earth satellite is its velocity
perpendicular to the surface of Earth.
Prelecture Reading Question 8.05 Part A When a rock tied to a string is whirled in a horizontal circle, doubling the speed _______.
quadruples the tension in the string
Multiple Choice Question 8.32 Part A A torque acting on an object tends to produce
rotation.
Prelecture Reading Question 7.10 Part A Fossil fuels, hydroelectric power, and wind power ultimately get their energy from _______.
the Sun
Prelecture Reading Question 9.06 Part A Which two factors mainly affect ocean tides on Earth? Check two answers.
the Sun the Moon
Multiple Choice Question 8.29 Part A Which jar will roll down an incline in the shortest time, an empty one or one filled with peanut butter?
the filled jar
Multiple Choice Question 10.14 Part A A hunter on level ground fires a bullet at an angle of 10 degrees below the horizontal while simultaneously dropping another bullet from the level of the rifle. Which bullet will hit the ground first?
the one fired
Prelecture Reading Question 7.02 Part A When one does twice the work in twice the time, the power expended is _______.
the same.
Prelecture Reading Question 7.08 Part A Recycled energy is mainly _______.
use of energy otherwise wasted
Reading Check 10.23 Part A What is the ratio of escape speed from Earth to circular orbital speed? Ignore air resistance.
1.41
Reading Check 7.14 Part A What will the kinetic energy of a pile driver ram be if it starts from rest and undergoes a 10 kJ decrease in potential energy?
10 kJ
Prelecture Reading Question 10.10 Part A Escape speed from Earth is any speed equal to or greater than __________.
11.2 km/s
Reading Check 7.20 Part A A force of 50 N is applied to the end of a lever, which is moved a certain distance. If the other end of the lever moves one-third as far, how much force does it exert?
150 N
Prelecture Reading Question 7.07 Part A When the useful energy output of a simple machine is 100 J, and the total energy input is 200 J, the efficiency is _______.
50 %.
Reading Check 7.22 Part A If an input of 100 J in a pulley system increases the potential energy of a load by 60 J, what is the efficiency of the system?
60%
Reading Check 8.20 Part A Why doesn't the Leaning Tower of Pisa topple over?
A vertical line through the center of gravity passes inside its support base.
Projectile Motion Tutorial Part A A ball is thrown vertically upward with an initial speed of 30 m/s. How long does it take to come back down? Part B A ball is thrown vertically upward with an initial speed of 10 m/s, and it reaches a maximum height of 5 m. If the ball is thrown vertically with an initial speed of 30 m/s, what would its maximum height be? Part C A ball is dropped from rest off a cliff, and it hits the ground in 4 seconds. How far did it drop? Part D A ball is kicked so that initially its horizontal velocity is 5 m/s and its vertical velocity is 10 m/s. When the ball is at its highest point above the ground, what is its horizontal velocity? Part E A bird is flying at a constant height 5 meters above the ground and drops an egg with an initial horizontal velocity of 3 m/s. How far does the egg travel horizontally before hitting the ground? Part F Three soccer balls (A, B and C) are kicked simultaneously. The initial speed of the balls is the same, but they are kicked at different angles. The trajectories of the balls are shown in the figure. Which ball hits the ground last?
A- 6 seconds B- 45 m C- 80 m D- 5 m/s E- 3 m F- Ball A kicked at a 60° angle
Video Tutor: Balancing a Meter Stick Part A Suppose we replace the mass in the video with one that is four times heavier. How far from the free end must we place the pivot to keep the meter stick in balance?
A- 90 cm (10 cm from the weight)
Orbital Motion Tutorial Part A Why do the planets orbit the Sun and NOT crash into the Sun? Part B Consider the trajectories in the figure, which are shown looking directly down. Which trajectories are possible orbital paths? Part C A satellite orbits Earth with the trajectory shown in the figure. Which points are acceptable locations for Earth? Part D The orbital path of a satellite is shown in the figure. In which of the marked positions does the satellite have the LOWEST speed?
A- Although the planets experience a force of gravity from the Sun, because they are moving, their trajectories bend around the Sun rather than lead directly into the Sun. B- trajectories 1 and 3 only C- point 2 only D- location C
Think And Discuss 8.114 Part A With respect to Diana's finger, where is the center of mass of the plastic bird?
A- At the point at which bird rests on Diana's finger.
Prelecture Video: Moment of Inertia Part A A baseball bat can be rotated around many different axes of rotation. Three such possibilities are shown in (Figure 1) . Rank the baseball bat's moment of inertia about each of these three axes of rotation. Rank the moment of inertia from largest to smallest and overlap axes labels if the same. Part B Given the same baseball bat and possible axes of rotation shown in (Figure 1) , for which axis of rotation would it be the easiest to rotate the bat from rest? Part C A girl spins around in a circle trying to make herself dizzy. Without changing her position, she starts spinning twice as fast. By how much did her rotational kinetic energy change? Part D A solid sphere and a hollow sphere (spherical shell) of the same mass and same radius rotate with the same amount of kinetic energy. Which one is rotating faster?
A- B,A,C B- C C- It quadrupled. D- the solid sphere
Video: Projectile Motion Part A When Dr. Hewitt releases the two projectiles, which one hits the ground first? Part B When Dr. Hewitt releases the two objects, how can we tell whether one of the objects hits the ground first or whether they both hit at the same time? Part C Why do the two objects hit the table at the relative times that they do?
A- Both balls hit the ground at the same time. B- We are able to hear the two balls fall. C- Gravity pulls the same amount on both, and they both drop the same distance.
Interactive Figure: Torque, Force, and Lever Arm Part A How does the lever arm change if you decrease the angle of the force? Part B How does the lever arm change when you decrease the distance to the nut? Part C How does the force needed to turn the wrench change if you increase the lever arm?
A- It decreases. B- It decreases. C- It decreases.
Video: Rotational Inertia With a Weighted Rod Part A Is it easier to balance a long rod with a mass attached to it when the mass is closer to your hand or when the mass is farther away? Part B How does the rotational inertia of the rod with the mass toward the bottom compare with the rotational inertia of the mass toward the top? Part C Why does the rotational inertia of the rod with the attached mass closer to your hand compare the way it does with the rotational inertial of the rod with the attached mass farther away? Part D Is it easier for a circus performer to balance a long rod held vertically with people hanging off the other end, or the same long rod without the people at the other end, and why?
A- It is easier when the mass is farther from your hand. B- The rotational inertia of the rod with the mass closer to the top is greater than the rotational inertia of the rod with the mass closer to the bottom. C- Rotational inertia depends on whether the mass is farther or closer to the point of rotation. The farther the mass is, the higher the rotational inertia. D- It is easier for the performer to balance a long rod held vertically with people at the other end because the rotational inertia is greater.
Video Tutor: Chin Basher? Part A Suppose our experimenter repeats his experiment on a planet more massive than Earth, where the acceleration due to gravity is g=30 m/s2. When he releases the ball from chin height without giving it a push, how will the ball's behavior differ from its behavior on Earth? Ignore friction and air resistance. (Select all that apply.)
A- It will take less time to return to the point from which it was released.
Rotational Motion Tutorial Part A Joe lives on the equator, and Sally lives in Alaska. Which person has the higher angular velocity due to Earth's rotation? Part B Joe lives on the equator, and Sally lives in Alaska. Which person has the higher speed due to Earth's rotation? Part C Suppose Sally lived on the equator of a planet that had a radius twice that of Earth's radius and that rotated with twice the angular velocity (so one day would be 12 hours long). Sally's speed on this planet would be _______ Joe's speed (who lives on Earth's equator). Part D Shown in the figure is a view of a door from above. Three forces are shown acting on the door. Which force is causing the largest torque on the door? Part E Door B is twice as wide as door A, but both doors have the same height and the same mass. A person pushes on the edge of the two doors with the same force. Which door opens more quickly? Part F A girl weighs 60 pounds and is sitting on the teeter-totter 3 m from the center. How far from the center should a 180-pound boy sit so that the teeter-totter balances?
A- Joe and Sally have the same angular velocity. B- Joe C- Four times faster D- Force A E- Door A F 1.0 Meters
Video Tutor: Ball Fired Upward from Moving Cart Part A The crew of a cargo plane wishes to drop a crate of supplies on a target below. To hit the target, when should the crew drop the crate? Ignore air resistance.
A- Part A The crew of a cargo plane wishes to drop a crate of supplies on a target below. To hit the target, when should the crew drop the crate? Ignore air resistance.
Video: Bowling Ball and Conservation of Energy Part A What happens the first time Dr. Hewitt lifts the bowling ball near his teeth and lets go? Part B Why does the bowling ball behave the way it does the first time Dr. Hewitt lifts the bowling ball near his teeth and lets go? Part C What happens the second time Dr. Hewitt lifts the bowling ball near his teeth and gives it a push? The ball leaves Dr. Hewitt and returns to him, going past the point where it was released.
A- The ball returns to Dr. Hewitt, stopping almost exactly at the point where it was released. B- All of the initial energy of the ball was converted completely back to potential energy when the ball returned. C- The ball leaves Dr. Hewitt and returns to him, going past the point where it was released. D- The extra energy from the push is converted into kinetic energy, which is then converted into more potential energy at the end of the motion than the ball had when it was released
Video Tutor: Dropped and Thrown Balls Part A Which ball (if either) has the greatest speed at the moment of impact?
A- The ball thrown horizontally
Energy Tutorial Part A A person has a choice of sliding down one of three slides, which are shown to the left. All slides start at the same height above ground. Ignoring friction, for which slide will the final speed of the person at the bottom be the highest? (Figure 1) Part B A 2-kg ball is moving with a speed of 4 m/s, and a 4-kg ball is moving with a speed of 2 m/s. What can you conclude about the kinetic energies of the two balls? Part C A ball is dropped from a distance 5 m above the ground, and it hits the ground with a certain speed. If the same ball is dropped from a distance 10 m above ground, its final speed will be ________. Part D An object is dropped from a distance of R=2REarth from Earth's center, and it falls down and hits Earth's surface. If the object is dropped from a distance R=3REarth (twice as far away from Earth's surface), its kinetic energy right before hitting the ground would be _____ what it was before. (Figure 2) Part E If an object had a temperature of absolute zero (0 K), its ______________. Part F A star forms when gravity causes a gas cloud to collapse. As the size of the cloud decreases, the temperature of the cloud _____________. Part G A positron is a particle similar to an electron, but with the opposite charge of an electron. If a positron and an electron collide, sometimes both the electron and positron disappear (annihilate), and two photons are created. This is an example of ____________. Part H A gas containing both hydrogen molecules (each molecule contains two hydrogen atoms) and helium atoms has a temperature of 300 K. How does the average speed of the hydrogen molecules compare to the helium atoms?
A- The final speed will be the same, regardless of which slide is used. B- The 2-kg ball has more kinetic energy. C- 1.4 times as fast D- greater than the original value but less than twice E- thermal energy would be zero F- increases G- the conversion of rest-mass energy into radiative energy H- The average speed of the hydrogen molecules is faster than that of the helium atoms, but it is less than two times faster.
Video: Apparent Weightlessness Part A How does the gravity in the Space Shuttle compare with the gravity on Earth's surface? Part B Why does the gravity in the Space Shuttle compare with the gravity on Earth the way it does? Part C Why do the astronauts in the Space Shuttle float around?
A- The gravity in the Space Shuttle is approximately equal to the gravity on the surface of the Earth. B- The Space Shuttle is about the same distance from the center of the Earth than from the surface of the Earth. C- The Space Shuttle is in free fall, so the shuttle and the astronauts inside it are continuously falling toward the Earth. They thus experience apparent weightlessness.
Video: Weight in an Elevator Part A Predict how the upward force exerted on the feet by the scale will compare to the weight of the man if the elevator is moving upward at a constant speed. Part B Predict how the upward force exerted on the feet by the scale will compare to the man's weight if the elevator is moving downward at a constant speed. Part C Predict how the upward force exerted on the feet by the scale will compare to the man's weight if the elevator is accelerating upward. Part D Predict how the upward force exerted on the feet by the scale will compare to the man's weight if the elevator is accelerating downward.
A- The upward force on the feet will be equal to the man's weight. B- The upward force on the feet will be equal to the man's weight. C- The upward force on the feet will exceed the man's weight. D- The upward force on the feet will be less than the man's weight.
Motion and Gravity Tutorial Part A A parachutist is falling toward the ground. The downward force of gravity is exactly equal to the upward force of air resistance. Which statement is true? Part B A kilogram is a measure of an object's ________. Part C Why would a bowling ball and a small marble fall down to the surface of the Moon at the same rate? Part D If you stood on a planet having a mass four times that of Earth, and a radius two times that of Earth, how much would you weigh on that planet? Part E Imagine that Earth had an identical twin planet, "Farth", which is twice as far away from the Sun as Earth is. Compared to the force of gravity that Earth exerts on the Sun, how strong is the force of gravity that Farth exerts on the Sun? Part F Suppose the Sun suddenly shrunk, reducing its radius by half (but its mass remaining the same). The force of gravity exerted on the Earth by the Sun would _________. Part G If one person is pushing to the right on a 300-kg cart with a force of 200 N, and another person is pushing to the left on the same cart with a force of 100 N, what is the acceleration of the cart? Part H Object A has three times as the mass of object B. Identical forces are exerted on the two objects. Which statement is true?
A- The velocity of the parachutist is not changing with time. B- Mass C- The force of gravity is proportional to the object's mass. D- the same as your weight on Earth E- one-fourth as strong F- remain the same G- 0.33 m/s/s H- The acceleration of object B is three times that of object A.
PhET Tutorial: Energy Skate Park Part A Click on the Energy vs. Position button, and de-select all forms of energy except kinetic energy. Where on the track is the skater's kinetic energy the greatest? Part B Change the Energy vs. Position graph to display only potential energy. As the skater is skating back and forth, where does the skater have the most potential energy? Part C Because we are ignoring friction, no thermal energy is generated and the total energy is the mechanical energy, the kinetic energy plus the potential energy: E=K+U. Display the total energy in the Energy vs. Position graph. As the skater is skating back and forth, which statement best describes the total energy? Part E Based on the previous question, which statement is true? Part F If the skater started from rest 4 m above the ground (instead of 7m), what would be the kinetic energy at the bottom of the ramp (which is still 1 m above the ground)? Part G One common application of conservation of energy in mechanics is to determine the speed of an object. Although the simulation doesn't give the skater's speed, you can calculate it because the skater's kinetic energy is known at any location on the track. Consider again the case where the skater starts 7 m above the ground and skates down the track. What is the skater's speed when the skater is at the bottom of the track? Express your answer numerically in meters per second to two significant figures. Part H When the skater starts 7 m above the ground, how does the speed of the skater at the bottom of the track compare to the speed of the skater at the bottom when the skater starts 4 m above the ground? Part I Change the potential energy reference line to be 7 m above the ground (select the Potential Energy Reference option, and click and drag on the dashed blue horizontal line to the 7 m grid line). Place the skater on the track 7 m above the ground, and let the skater go. Part J At the bottom of the hill, how does the kinetic energy compare to the case when the potential energy reference was the ground and the skater was released 7m above the ground? Part K Click Tracks in the upper-left corner of the window, and select Double Well (Roller Coaster). Then, click and drag on the blue circles to stretch and/or bend the track to make it look like that shown below.
A- at its maximum value at the lowest point of the track. B- at its maximum value at the locations where the skater turns and goes back in the opposite direction. C- the same at all locations of the track. E- equal to the amount of potential energy loss in going from the initial location to the bottom. F- 2205 J G- 11 m/s H- higher, but less than twice as fast. I- equal to zero. J- the same as the case when the potential energy reference was the ground. K- 1, 3, 5 AND 2 OVER LAP
Video: Difference Between Torque and Weight Part A Where is the center of gravity of the broom that Dr. Hewitt holds up? Part B When Dr. Hewitt cuts the broom right through the center of gravity, how do the weights of the two sides of the broom compare? Part C How does the torque due to the weight of one side of the broom exerted around the balance point compare with the torque exerted by the weight of the other side of the broom around the balance point?
A- at the balance point B- The shorter side, where the bristles of the broom are, has a greater weight than the handle. C- The torque due to the weight of the shorter side (the bristles of the broom) is equal in magnitude to the torque due to the weight of the longer side, and opposite in direction.
Think And Discuss 7.112 Part A Select the correct equations that show why the mass of block B is 24 kg .
A- mB⋅g=2T=2mA⋅g. Hence, mB=2mA=24kg.
Think And Explain 8.79 Part A The centers of gravity of the three trucks parked on a hill are shown by the Xs. Which truck(s) will tip over? (Figure 1) Check all that apply.
A- the left truck
Tides Tutorial Part A Each day _______________. Part B Which of the diagrams in the figure best illustrates the correct position of the Earth relative to its ocean mass due to tides? Part C The Moon's gravitational pull is _________. Part D Approximately how much time passes between low and high tide? Part E A high tide can occur __________. Part F If there were no Moon, would there still be tides on Earth? Part G How do the high tides during a full moon compare to high tides during a new moon? Part H Which of the following lists correctly gives, in increasing order, the height of the high tides that occur during particular lunar phases? (Ties are denoted by parentheses.)
A- there are two high tides and two low tides B- B C- strongest on the side of Earth closest to the Moon D- 6 Hours E- When the moon is high over head. F- Yes, because the Sun's gravity still has an influence. G- The high tides during a full moon are roughly the same as the high tides during a new moon. H- (first quarter, third quarter), (new, full)
Think And Solve 8.45 Part A What torque are you exerting? Express your answer to two significant figures and include the appropriate units. Part B If you move your hand inward to be only 0.10 m from the bolt, find the force that you should exert to achieve the same torque. Express your answer to two significant figures and include the appropriate units. Part C Do your answers depend on the direction of your push relative to the direction of the wrench handle?
A- τ = 21 N⋅m B- F = 210 N C- YES
Reading Check 10.09 Part A How can a projectile "fall around the Earth"?
All of the above.
Reading Check 10.01 Part A What exactly is a projectile?
An object that continues in motion by its own inertia
Reading Check 8.28 Part A Distinguish between linear momentum and angular momentum.
Angular momentum depends on the distribution of mass, whereas linear momentum depends on the total mass.
Reading Check 9.20 Part A Why are all tides greatest at the time of a full Moon or new Moon?
At full Moon and new Moon, the tides from the Moon and the Sun add because they are in line with Earth.
Reading Check 8.08 Part A Consider three axes of rotation for a pencil: along the lead, at right angles to the lead at the middle, and at right angles to the lead at one end. Rate the rotational inertias about each axis from smallest to largest.
Axis along the lead, through the center, through one end
Reading Check 8.10 Part A Why does bending your legs when running enable you to swing your legs to and fro more rapidly?
Bending your legs shortens them, thus reducing rotational inertia.
Video Tutor: Walking the plank Part A In the video, the torque due to the mass of the plank is used in the calculations. For this question, ignore the mass of the board. Rank, from largest to smallest, the mass m needed to keep the board from tipping over. To rank items as equivalent, overlap them.
D, Overlap A,B, C
Reading Check 7.19 Part A If a machine multiplies force by a factor of 4, what other quantity is diminished, and by how much?
Distance is diminished to one-quarter.
Prelecture Reading Question 9.07 Part A Earth's gravitational field is strongest at _______.
Earth's surface
Plug And Chug 7.40 Part A Select the correct equations that show that a machine that has an input of 100 J and an output of 70 J is 70 % efficient.
Efficiency η=(Eout/Ein)⋅100%=((70J)/(100J))⋅100%=70%
Reading Check 7.05 Part A Exactly what is it that enables an object to do work?
Energy
Reading Check 9.13 Part A When is your weight measured as mg?
For a non-accelerating mass near the surface of Earth
Video Tutor: Spinning Person Drops Weights Part A The experimenter from the video rotates on his stool, this time holding his empty hands in his lap. You stand on a desk above him and drop a long, heavy bean bag straight down so that it lands across his lap, in his hands. What happens?
He spins slower.
Reading Check 8.30 Part A If a skater who is spinning pulls her arms in so as to reduce her rotational inertia by half, by how much will her angular momentum change? By how much will her rate of spin change?
Her angular momentum does not change. Her spin rate doubles.
Reading Check 7.10 Part A When the speed of a moving car is doubled, how much more kinetic energy does it have?
It has four times as much.
Reading Check 8.15 Part A If you toss a stick into the air, it appears to wobble all over the place. Specifically, about what place does it wobble?
It will rotate about the center of mass.
Reading Check 7.07 Part A A car is raised a certain distance in a service-station lift, thus giving it potential energy relative to the floor. If it were raised twice as high, how much more potential energy would it have?
It would have twice as much potential energy.
Reading Check 9.27 Part A If Earth shrank, but there was no change in its mass, then what would happen to your weight at the surface?
It would increase.
Reading Check 7.06 Part A If both sacks in the preceding question are lifted their respective distances in the same time, how does the power required for each compare? How about for the case in which the lighter sack is moved the same distance in half the time?
Lifted in the same time, the power is the same. The light sack moving in half the time requires double the power.
Reading Check 9.11 Part A Would the springs inside a bathroom scale be more compressed or less compressed if you weighed yourself in an elevator that was accelerating upward? Downward?
More compressed while accelerating upward, but less compressed while accelerating downward
Reading Check 8.05 Part A How is a flywheel constructed to maximize its rotational inertia?
Most of the mass is concentrated far from the axis.
Reading Check 9.26 Part A Newton viewed the curving of the path of a planet as being caused by a force acting on the planet. How did Einstein view the curved path of a planet?
Moving in curved 4-dimensional spacetime
Think And Explain 8.65 Part A Can a force produce a torque when there is no lever arm?
NO
Think And Solve 9.41 Part A Is there change in the force of gravity between two objects when their masses are doubled and the distance between them is also doubled?
NO
Reading Check 9.30 Part A What was the cause of perturbations discovered in the orbit of the planet Uranus? What later discovery did this lead to?
Neptune caused the perturbations, and later Pluto was discovered.
Prelecture Reading Question 7.09 Part A Which energy production method does not ultimately depend on the Sun?
Nuclear fission
Plug And Chug 7.32 Part A Select the correct equations that show that 50 W of power is required to give a brick 100 J of PE in a time of 2 s .
P=W/t=(100J)/(2s)=50W
Think And Explain 8.57 Dan and Sue cycle at the same speed. The tires on Dan's bike are larger in diameter than those on Sue's bike. Which wheels, if either, have the greater rotational speed?
Sue's wheels have the greater rotational speed.
Reading Check 9.17 Part A Describe how the gravitational forces from the Sun and the Moon compare from one side of Earth to the other.
The Sun exerts a stronger force on the side of Earth nearest the Sun, and the Moon exerts a stronger force on the side nearest the Moon.
Video Tutor: Ball Fired from Cart on Incline Part A Consider the video demonstration that you just watched. A more complete explanation of what you saw will be possible after covering Newton's laws. For now, consider the following question: How would the result of this experiment change if we replaced the ball with another one that had half the mass? Ignore air resistance.
The ball would still land in the cart.
Reading Check 8.06 Part A Inertia depends on mass; rotational inertia depends on mass and something else. What?
The distribution of mass about the axis of rotation
Reading Check 8.09 Part A Which is easier to get swinging: a baseball bat held at the narrow end or a bat held closer to the massive end (choked up)? Also answer for a short bat versus a long bat.
The easiest is choked up and a short bat.
Reading Check 7.15 Part A An apple hanging from a limb has potential energy because of its height. If it falls, what becomes of this energy just before it hits the ground? When it hits the ground?
The energy is kinetic energy before it hits the ground; it is thermal energy after.
Reading Check 9.08 Part A How does the force of gravity between two bodies change when the distance between them is doubled?
The force decreases to ¼ of its initial value.
Prelecture Reading Question 9.02 Part A What happens to the force of attraction between two planets when the masses of both are doubled?
The force quadruples.
Video Tutor: Range of a Gun at Two Firing Angles Part A Which projectile spends more time in the air, the one fired from 30∘ or the one fired from 60∘?
The one fired from 60∘
Reading Check 9.02 Part A What is the Newtonian synthesis?
The union of terrestrial laws and cosmic laws
Reading Check 8.25 Part A If you are not wearing a seat belt in a car that rounds a curve, and you slide across your seat and slam against a car door, what kind of force is responsible for your slide: centripetal, centrifugal, or no force?
There is no force as viewed by someone outside the car. To them you move in a straight line.
Reading Check 8.14 Part A How do clockwise and counterclockwise torques compare when a system is balanced?
They are equal in magnitude and opposite in direction.
Reading Check 9.15 Part A Why are occupants of the International Space Station weightless?
They are in free fall.
Reading Check 8.22 Part A When you whirl a can at the end of a string in a circular path, what is the direction of the force you exert on the can?
Toward the center of the circle
Plug And Chug 7.29 Part A Select the correct equations that show that 4.8 J of work is done when a force of 4.0 N moves a book 1.2 m.
W=F⋅d=(4.0N)⋅(1.2m)=4.8J
Plug And Chug 7.38 Part A Select the correct equations that show that 72 J of work is done when a 9.0-kg block of ice is moved from rest to a speed of 4.0 m/s.
W=mv2/2=((9.0kg)⋅(4.0m/s)2)/2=72J
Reading Check 9.10 Part A Where do you weigh more: at the bottom of Death Valley or atop one of the peaks of the Sierra Nevada? Why?
You weigh more in Death Valley because you are closer to the center of Earth.
Reading Check 7.03 Part A How much work is done on a satellite in a circular orbit about Earth?
Zero
Reading Check 9.25 Part A What would the magnitude of the gravitational field be anywhere inside a hollow, spherical planet?
Zero N/kg
Prelecture Reading Question 8.04 Part A The center of gravity of a basketball is located _______.
at its geometrical center
Multiple Choice Question 10.23 Part A When air drag affects the motion of projectiles, they don't travel
both of these
Prelecture Reading Question 7.04 Part A When traveling twice as fast your kinetic energy is increased _______.
by four.
Prelecture Reading Question 9.08 Part A Einstein's theory of gravitation, compared with Newton's, _______.
eliminates the role of force
Multiple Choice Question 7.7 Part A The unit kilowatt-hour is a unit of
energy.
Video Tutor: Ball Fired Upward from Accelerating Cart Part A Consider the video you just watched. Suppose we replace the original launcher with one that fires the ball upward at twice the speed. We make no other changes. How far behind the cart will the ball land, compared to the distance in the original experiment?
four times as far
Prelecture Reading Question 7.01 Part A The work that is done when twice the load is lifted twice the distance is _______.
four times as much.
Prelecture Reading Question 8.01 Part A The tangential speed on the outer edge of a rotating carousel is _______.
greater than toward the center
Prelecture Reading Question 8.02 Part A Rotational inertia about the midpoint of an object becomes greater with _______.
increased mass and increased distance to mass concentration
Prelecture Reading Question 10.01 Part A The horizontal and vertical components of velocity for a projectile are __________.
independent of each other
Reading Check 7.01 Part A What is the unit of work?
joule
Prelecture Reading Question 9.03 Part A The constant G in Newton's equation _______.
makes the units of measurement consistent
Multiple Choice Question 8.17 Part A Which of these animals has a quicker stride?
mouse
Prelecture Reading Question 9.05 Part A One's weightlessness in space has most to do with _______.
no support force
