Conceptual Physics Chapter 3
A mosquito flying at 3 m/s that encounters a breeze blowing at 3 m/s in the opposite direction has a speed of
0 m/s
An object covers a distance of 8 meters in the first second of travel, another 8 meters during the next second, and 8 meters again during the third second. Its acceleration in meters per second per second is approximately
0.
If a projectile is fired straight up at a speed of 10 m/s, the time it takes to reach the top of its path is about
1 second.
A vehicle undergoes acceleration when it
1) Changes its direction 2) Gains speed 3) Loses speed (ALL OF THE ABOVE)
A motorboat that normally travels at 8 km/h in still water heads directly across a 6-km/h flowing river. The resulting speed of the boat is about
10 km/h
What is the acceleration of a car moving along a straight road that increases its speed from 0 to 100 km/h in 10 s?
10 km/h·s
If a freely falling object were equipped with a speedometer, its speed reading would increase each second by about
10 m/s.
If a freely falling object were somehow equipped with a speedometer, its speed reading would increase each second by about
10 m/s.
If you throw a ball straight downward (in the absence of air resistance), after leaving your hand its acceleration is
10 m/s^2
An 800-km/h airplane caught in a 60-km/h crosswind has a resultant speed of
100 km/h
A car accelerates at 2 meters/s/s. Assuming the car starts from rest, how far will it travel in 10 s?
100 m
A river 100 m wide flows due south at 1 m/s. A boat that travels 1 m/s relative to the water is pointed due east as it crosses from the west bank. The boat reaches the east bank
100 m farther south
An object falls freely from rest on a planet where the acceleration due to gravity is 20 meters per second squared. After 5 seconds, the object will have a speed of
100 m/s.
While you're in a bus that moves at 100 km/h, you walk from the back to the front at 10 km/h. What is your speed relative to the road outside?
110 km/h
An airplane that flies at 100 km/h in a 100-km/h crosswind has a ground speed of
141 km/h
A river 100 m wide flows 1 m/s due south. A boat that travels 1 m/s relative to the water is pointed due east as it crosses from the west bank. Relative to its starting point, the boat travels
141 m
Phil leans over the edge of a cliff and throws a rock upward at 5 m/s. Neglecting air resistance, two seconds later the rock's speed is
15 m/s
D
18) While a car travels around a circular track at constant speed its A) acceleration is zero. B) velocity is zero. C) both of these. D) none of these.
If a stone falls to the bottom of a mineshaft in 6 seconds, then the depth of the shaft is about
180 m
If a projectile is fired straight up at a speed of 10 m/s, the total time to return to its starting position is about
2 seconds.
B
2) Which of the following is not a vector quantity? A) velocity B) speed C) acceleration D) None are vector quantities. E) All are vector quantities.
A horse gallops a distance of 10 kilometers in a time of 30 minutes. Its average speed is
20 km/h
The average speed of a horse that gallops 10 kilometers in 30 minutes is
20 km/h
When you walk at an average speed of 4 m/s, in 5 s you'll cover a distance of
20 m
An object at rest near the surface of a distant planet starts to fall freely. If the acceleration there is twice that of the Earth, its speed one second later would be
20 m/s
An object at rest near the surface of a distant planet starts to fall freely. If the acceleration there is twice that of the Earth, its speed one second later would be
20 m/s.
If a freely falling object were equipped with a speedometer on a planet where the acceleration due to gravity is 20 m/s2, then its speed reading would increase each second by
20 m/s.
If a freely falling object were somehow equipped with a speedometer on a planet where the acceleration due to gravity is 20 m/s/s, then its speed reading would increase each second by
20 m/s.
An object falls freely from rest on a planet where the acceleration due to gravity is twice as much as on Earth. In the first 5 seconds it falls a distance of
250 m
A ball freely falling at 20 m/s will in the next second have a speed of _______.
30 m/s
A pot that falls from a ledge and hits the ground 45 m below hits the ground at
30 m/s
If a rocket initially at rest accelerates at a rate of 50 m/s^2 for one minute, its speed will be
3000 m/s
What is the acceleration of a car that starts from rest and 5 seconds later reaches a speed of 20 m/s?
4 m/s^2
Ten seconds after starting from rest, a car is moving at 40 m/s. What is the car's acceleration?
4.0 m/s^2
At one instant a heavy object in air is moving upward at 50 meters per second. One second later its speed is approximately
40 m/s.
In its first second of free fall, a dropped softball will fall a vertical distance of _______.
5 m
One half second after starting from rest, a freely falling object will have a speed of about
5 m/s
Phil leans over the edge of a cliff and throws a rock upward at 5 m/s. Neglecting air resistance, one second later the rock's speed is
5 m/s
One half second after starting from rest, a freely falling object will have a speed of about
5 m/s.
C
50) The vertical height attained by a basketball player who achieves a hang time of a full 1 s is about A) 0.8 m. B) 1 m. C) 1.2 m. D) 2.5 m. E) more than 2.5 m.
A mosquito flying at 3 m/s that encounters a breeze blowing at 3 m/s in the same direction has a speed of
6 m/s
If a car accelerates from rest at 2 meters per second per second, its speed 3 seconds later will be about
6 m/s.
A
7) As an object freely falls downward, its A) velocity increases. B) acceleration increases. C) both of these. D) none of these.
A ball starting from rest at the top of an inclined plane accelerates at 2 m/s^2 and reaches the bottom of the plane in 3 seconds. What is the length of the plane?
9 m
D
9) If an object falling freely downward were somehow equipped with a speedometer on a planet where the acceleration due to gravity is 40 meters per second per second, then its speed reading would increase each second by A) 10 m/s. B) 20 m/s. C) 30 m/s. D) 40 m/s. E) depends on its initial speed.
If you drop an object, it will accelerate downward at a rate of 9.8 meters per second per second. If you instead throw it downwards, its acceleration (in the absence of air resistance) will be
9.8 meters per second per second.
less
A ball rolls along a horizontal track in a certain time. If the track has a dip in it, the time to roll the length of the track will be
directed downward
A ball tossed vertically upward rises, reaches its highest point, and then falls back to its starting point. During this time the acceleration of the ball is always
10 km/h
A bird flying at 8 km/h in a 6-km/h crosswind has a resultant speed of
the same for each bullet
A bullet is dropped into a river from a very high bridge at the same time as another bullet is fired straight downward from a rifle. Neglecting air resistance, the acceleration just before striking the water is
zero
A cart maintains a constant velocity of 100 m/s for 10 second. During this interval its acceleration is
5 km/h
A humming bird flying at 4 km/h that gets caught in a 3-km/h crosswind has a resultant speed of about
0 m/s
A mosquito flying at 3 m/s that encounters a breeze blowing at 3 m/s in the opposite direction has a speed of
6 m/s
A mosquito flying at 3 m/s that encounters a breeze blowing at 3 m/s in the same direction has a speed of
30 m/s
A pot that falls from a ledge and hits the ground 45 m below hits the ground at
100 m farther south
A river 100 m wide flows due south at 1 m/s. A boat that travels 1 m/s relative to the water is pointed due east as it crosses from the west bank. The boat reaches the east bank
20 m/s
An object at rest near the surface of a distant planet starts to fall freely. If the acceleration there is twice that of the earth, its speed one second later would be
100 m/s
An object falls freely from rest on a planet where the acceleration due to gravity is 20 m/s^2. After 5 seconds, the object will have a speed of
250 m
An object falls freely from rest on a planet where the accelerations due to gravity is twice as much as on earth. In the first 5 seconds it falls a distance of
What exactly is meant by a "freely falling" object?
An object in free fall falls under gravity alone with no friction.
get farther apart
As water drops fall at a steady rate from a leaking faucet they
How can you use the graph of velocity versus time to estimate the acceleration of the ball?
By estimating the value of the slope of the graph.
If an object falling freely were somehow equipped with an odometer to measure the distance it travels, then the amount of distance it travels each succeeding second would be
Greater than the second before.
6 m/s^2
If a car increases its velocity from zero to 60 m/s in 10 second, its acceleration is
20 m/s
If a freely falling object were equipped with a speedometer on a planet where the accleration due to gravity is 20 m/s^2, then its speed reading would increase each second by
3000 m/s
If a rocket initially at rest accelerates at a rate of 50 m/s^2 for one minute, its speed will be
greater than the second before
If an object falling freely were somehow equipped with an odometer to measure the distance it travels, then the amount of distance it travels each succeeding second would be
change by the same amount each second
If an object moves with constant acceleration, its velocity must
10 m/s^2
If you throw a ball straight downward (in the absence of air resistance), after leaving your hand its acceleration is
What is the gain in speed per second for a freely falling object?
It gains approximately 10 m/s.
14 m/s
Jogging Jake runs at 4 m/s along a train flatcar that moves at 10 m/s in the same direction. Jake's speed relative to the ground is
either depending on her running direction
Katelyn runs along the aisle of a train that moves at 8 m/s. Her speed relative to the floor is 3 m/s. Her speed relative to an observer at rest on the ground is
30 m/s
Neglecting air resistance, how fast must you toss a ball straight up in order for it to take 6 seconds to return to its initial level?
5 m/s
One half second after starting from rest, a freely falling object will have a speed of about
Neither, both hit with the same speed.
Phil Physiker standing at the edge of a cliff throws one ball straight up and another ball straight down, both with the same speed. Neglecting air resistance, which ball hits the ground below with the greater speed?
10 m
Phil leans over the edge of a cliff and throws a rock upward at 5 m/s. How far below the level from which it was thrown is the rock 2 seconds later?
5 m/s
Phil leans over the edge of a cliff and throws a rock upward at 5 m/s. Neglecting air resistance, one second later the rock's speed is
4.0 m/s^2
Ten seconds after starting from rest, a car is moving at 40 m/s. What is the car's acceleration?
range from zero to g
The accelerations possible for a ball on an inclined plane
none of the above
The distance of a freely falling object falls from rest in one half second is
(100-5) m.
The muzzle velocity of a bullet fired from a new rifle is 100 m/s. Neglecting air resistance, at the end of one second a bullet fired straight up into the air will have traveled a distance of
2 s
The total time it takes a projectile fired straight up at 10 m/s to reach the top of its path and return to its starting point is about
1.2 m
The vertical height attained by a basketball player who achieves a hang time of a full 1 s is about
more than 100 m/s
Twelve seconds after starting from rest, a freely falling cantelope has a speed of
Calculate the average speed of a cheetah that runs 150 meters in 6.0 seconds.
Vave = 25 ms
speed
Which of the following is not a vector quantity?
speed
While an iron block near the earths surface is in free fall it undergoes an increase in
against the breeze at 2 m/s
You're at rest in a hammock when a hungry mosquito sees an opportunity for lunch. A mild 2-m/s breeze is blowing. If the mosquito joins you for lunch it should hover over you by flying
vector quantity
a quantity that has magnitude and direction
scalar quantity
a quantity that has only a magnitude, not a direction
It takes 6 seconds for a stone to fall to the bottom of a mine shaft. How deep is the shaft?
about 180 m
Galileo discovered that when air resistance can be neglected, all objects fall with the same _______.
acceleration
A freely-falling watermelon falls with constant
acceleration.
Disregarding air resistance, objects fall with constant
acceleration.
velocity
an object's speed and direction of motion
If an object moves with constant acceleration, its velocity must
change by the same amount each second.
Calculate the vertical distance an object dropped from rest covers in 14s of free fall.
d = 980 m
A ball tossed vertically upward rises, reaches its highest point, and then falls back to its starting point. During this time the acceleration of the ball is always
directed downward.
The difference between speed and velocity involves _______.
direction
The difference between speed and velocity involves
direction.
A bullet is dropped from the top of the Empire State Building while another bullet is fired downward from the same location. Neglecting air resistance, the acceleration of
each bullet is 9.8 meters per second per second.
If an object falling freely were somehow equipped with an odometer to measure the distance it travels, then the amount of distance it travels each succeeding second would be
greater than the second before.
speed
how fast an object moves; the distance traveled per unit of time
The distance a freely falling bowling ball falls each second
increases.
In each second of fall, the distance a freely falling object will fall is
increasing.
A speedometer normally measures _______.
instantaneous speed
A speedometer normally measures
instantaneous speed.
free fall
motion under the influence of gravity only
The distance a freely falling object falls from rest in one-half second is
none of the above (5 m)
The accelerations possible for a ball on an inclined plane
range from zero to g.
An apple drops from a tree and hits the ground in 1.6s . Calculate how far it falls.
s = 13 m
Calculate the distance (in km) that Larry runs if he maintains an average speed of 9.3km/h for 1 hour.
s = 9.3 km
While an iron block near the Earth's surface is in free fall, it undergoes an increase in
speed.
acceleration
the rate at which velocity changes with time; the change in velocity may be in magnitude, or direction or both
A ball rolling down an inclined plane each second picks up
the same amount of speed each second.
A ball is thrown upwards and returns to the same location. Compared with its initial speed its speed when it returns is about
the same.
A ball is thrown upwards and returns to the same position. Compared with its original speed after release, its speed when it returns is about
the same.
A rock dropped from a 5-m height accelerates at 10 m/s2 and strikes the ground 1 s later. If the rock is dropped from a height of 2.5 m, its acceleration of fall is
the same.
instantaneous speed
the speed at any instant
average speed
the total distance traveled divided by the time of travel
What is the instantaneous velocity of a freely falling object 14s after it is released from a position of rest?
v = -140 ms
What is its average velocity during this 14-s interval?
v = -69 ms
An object is dropped from rest and falls freely. After 7.8s , calculate its instantaneous speed.
v = 78 ms
Calculate your walking speed when you step 1.0 meter in 0.55 second.
v = 1.8 ms
While an object near the Earth's surface is in free fall, its
velocity increases
When a rock thrown straight upwards gets to the exact top of its path, its
velocity is zero and its acceleration is about 10 meters per second per second.
A car maintains a constant velocity of 100 km/hr for 10 seconds. During this interval its acceleration is
zero.
A cart maintains a constant velocity of 100 m/s for 10 seconds. During this interval its acceleration is
zero.
A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are neglected, the force required to keep the puck sliding at constant velocity is
zero.
The time it takes a car to attain a speed of 30 m/s when accelerating from rest at 2 m/s2 is
15 s
A
1) Galileo's use of inclined planes allowed him to effectively A) slow down the acceleration of free fall. B) increase the acceleration beyond that of free fall. C) eliminate the acceleration of free fall. D) all of these. E) none of these.
While a car travels around a circular track at a constant speed, its
1) Inertia is zero 2) Velocity is zero 3) Acceleration is zero (NONE OF THE ABOVE)
Neglecting air resistance, a bullet fired straight down from the top of a high cliff has an acceleration of
10 m/s^2
When a ball thrown straight upwards reaches the very top of its path, its acceleration is
10 m/s^2
C
10) If an object falling freely downward were somehow equipped with an odometer to measure the distance it travels, then the amount of distance it travels each succeeding second would be A) constant. B) less and less. C) greater than the second before.
C
11) Ten seconds after starting from rest, an object falling freely downward will have a speed of about A) 10 m/s. B) 50 m/s. C) 100 m/s. D) more than 100 m/s.
B
12) If an object falls with constant acceleration, the velocity of the object must A) be constant also. B) continuously change by the same amount each second. C) continuously change by varying amounts depending on its speed. D) continuously decrease. E) none of these.
B
13) A heavy object and a light object are dropped at the same time from rest in a vacuum. The heavier object reaches the ground A) sooner than the lighter object. B) at the same time as the lighter object. C) later than the lighter object.
What is the speed over the ground of an airplane flying at 100 km/h relative to the air caught in a 100-km/h right-angle crosswind?
141 km/h
D
17) A ball tossed vertically upward rises, reaches its highest point, and then falls back to its starting point. During this time the acceleration of the ball is always A) in the direction of motion. B) opposite its velocity. C) directed upward. D) directed downward.
D
19) A car accelerates from rest at 2 meters per second per second. What is its speed 3 seconds after the car starts moving? A) 2 m/s B) 3 m/s C) 4 m/s D) 6 m/s E) none of these
A ball starting from rest at the top of an inclined plane gains a speed of 2 m/s for each second it rolls. What is its acceleration down the incline?
2 m/s^2
The total time it takes a projectile fired straight up at 10 m/s to reach the top of its path and return to its starting point is about
2 s
C
20) A ball is thrown upwards and caught when it comes back down. Neglecting air resistance, its speed when caught is A) more than the speed it had when thrown upwards. B) less than the speed it had when thrown upwards. C) the same as the speed it had when thrown upwards.
A
21) An object travels 8 meters in the first second of travel, 8 meters again during the second second of travel, and 8 meters again during the third second. Its acceleration in meters per second per second is A) 0. B) 5. C) 8. D) 10. E) more than 10.
D
22) At one instant an object in free fall is moving downward at 50 meters per second. One second later its speed is about A) 25 m/s. B) 50 m/s. C) 55 m/s. D) 60 m/s. E) 100 m/s.
E
23) At one instant an object in free fall is moving upward at 50 meters per second. One second later its speed is about A) 100 m/s. B) 60 m/s. C) 55 m/s. D) 50 m/s. E) 40 m/s.
B
25) A ball is thrown upwards and caught when it comes back down. In the presence of air resistance, the speed with which it is caught is A) more than the speed it had when thrown upwards. B) less than the speed it had when thrown upwards. C) the same as the speed it had when thrown upwards.
C
26) Starting from rest, the distance a freely-falling object will fall in 0.5 seconds is about A) 0.5 m. B) 1.0 m. C) 1.25 m. D) 5.0 m. E) none of these.
C
27) One half second after starting from rest, a freely-falling object will have a speed of about A) 20 m/s. B) 10 m/s. C) 5 m/s. D) 2.5 m/s. E) none of these.
E
28) An object falls freely from rest on a planet where the acceleration due to gravity is 20 meters per second squared. After 5 seconds, the object will have a speed of A) 5 m/s. B) 10 m/s. C) 20 m/s. D) 50 m/s. E) 100 m/s.
B
30) An apple falls from a tree and hits the ground 5 meters below. It hits the ground with a speed of about A) 5 m/s. B) 10 m/s. C) 15 m/s. D) 20 m/s. E) not enough information given to estimate.
C
31) It takes 6 seconds for a stone to fall to the bottom of a mine shaft. How deep is the shaft? A) about 60 m B) about 120 m C) about 180 m D) more than 200 m
B
32) If you drop an object, it will accelerate downward at a rate of 9.8 meters per second per second. If you instead throw it downwards, its acceleration (in the absence of air resistance) will be A) less than 9.8 meters per second per second. B) 9.8 meters per second per second. C) greater than 9.8 meters per second per second.
D
33) In each second of fall, the distance a freely falling object will fall is A) about 5 m. B) about 10 m. C) the same, but not 5 m or 10 m. D) increasing. E) none of these.
B
36) Consider drops of water that leak from a dripping faucet. As the drops fall they A) get closer together. B) get farther apart. C) remain at a relatively fixed distance from one another.
C
37) Disregarding air drag, how fast must you toss a ball straight up in order for it to take 2 seconds to return to the level from which you tossed it? A) 5 m/s B) 7.5 m/s C) 10 m/s D) 15 m/s E) 20 m/s
B
38) A car accelerates at 2 meters per second per second. Assuming the car starts from rest, how much time does it need to accelerate to a speed of 30 m/s? A) 2 seconds B) 15 seconds C) 30 seconds D) 60 seconds E) none of these
D
39) A car accelerates from rest for 5 seconds until it reaches a speed of 20 m/s. What is the car's acceleration in meters per second per second? A) 1 B) 2 C) 3 D) 4 E) 5
C
4) The two measurements necessary for calculating average speed are A) acceleration and time. B) velocity and time. C) distance and time. D) distance and acceleration. E) velocity and distance.
At one instant a heavy object in air is moving upward at 50 m/s. One second later its speed is approximately
40 m/s
C
40) Ten seconds after starting from rest, a car is moving at 40 m/s. What is the car's acceleration in meters per second per second? A) 0.25 B) 2.8 C) 4.0 D) 10 E) 40
B
44) A bullet is fired straight down from the top of a high cliff. Neglecting air resistance, the acceleration of the bullet in meters per second per second is A) less than 9.8. B) 9.8. C) more than 9.8.
C
45) A bullet is dropped into a river from a very high bridge. At the same time, another bullet is fired from a gun, straight down towards the water. Neglecting air resistance, the acceleration just before striking the water A) is greater for the dropped bullet. B) is greater for the fired bullet. C) is the same for each bullet. D) depends on how high they started. E) none of these.
What is the effect of air resistance on the acceleration of falling objects?
Air resistance decreases the acceleration of falling objects.
If a car moves with a constant velocity, does it also move with a constant speed?
Yes, because constant velocity requires constant speed in the same direction.
Galileo discovered that when air resistance can be neglected, all objects fall with the same
acceleration.
When we are talking about how quickly "how fast" changes, we're talking about
acceleration.
An object covers a distance of 8 meters in the first second of travel, another 8 meters during the next second, and 8 meters again during the third second. Its acceleration is
0 m/s^2
A cart changes its speed from 90 m/s to 100 m/s in 10 seconds. During this interval its acceleration is
1 m/s^2
C
24) Disregarding air resistance, objects fall with constant A) velocity. B) speed. C) acceleration. D) distances each successive second.
C
29) An object falls freely from rest on a planet where the acceleration due to gravity is 20 meters per second squared. In the first 5 seconds it falls a distance of A) 100 m. B) 150 m. C) 250 m. D) 500 m. E) none of these.
A
8) A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are neglected, the force required to keep the puck sliding at constant velocity is A) zero newtons. B) equal to the weight of the puck. C) the weight of the puck divided by the mass of the puck. D) the mass of the puck multiplied by 9.8 meters per second per second. E) none of these.
B
14) If a car increases its velocity from zero to 60 km/h in 10 seconds, its acceleration is A) 3 km/h s. B) 6 km/h s. C) 10 km/h s. D) 60 km/h s. E) 600 km/h s.
C
15) If a rocket initially at rest accelerates at a rate of 50 m/s2 for one minute, its speed will be A) 50 m/s. B) 500 m/s. C) 3000 m/s. D) 3600 m/s. E) none of these.
B
16) Drop a rock from a 5-m height and it accelerates at 10 m/s2 and strikes the ground 1 s later. Drop the same rock from a height of 2.5 m and its acceleration of fall is A) about half. B) the same. C) more.
A
3) An airplane that flies at 100 km/h with a 10 km/h tailwind travels at 110 km/h relative to the ground. If it instead flies into a 10 km/h headwind, its groundspeed is A) 90 km/h. B) 100 km/h. C) 110 km/h. D) 120 km/h.
What is the average speed in kilometers per hour of a horse that gallops a distance of 15 km in a time of 30 min?
30 km/h
A
34) If a projectile is fired straight up at a speed of 10 m/s, the time it takes to reach the top of its path is about A) 1 second B) 2 seconds C) 10 seconds D) not enough information to estimate
B
35) If a projectile is fired straight up at a speed of 10 m/s, the total time to return to its starting position is about A) 1 second. B) 2 seconds. C) 10 seconds. D) 20 seconds. E) not enough information to estimate.
B
41) When a rock thrown straight upwards gets to the exact top of its path, its A) velocity is zero and its acceleration is zero. B) velocity is zero and its acceleration is about 10 meters per second per second. C) velocity is about 10 m/s and its acceleration is zero. D) velocity is about 10 m/s and its acceleration is about 10 meters per second per second. E) none of these.
C
42) A bullet is dropped from the top of the Empire State Building while another bullet is fired downward from the same location. Neglecting air resistance, the acceleration of A) the fired bullet is greater. B) the dropped bullet is greater. C) each bullet is 9.8 meters per second per second.
A
43) The muzzle velocity of a certain gun is 100 m/s. Neglecting air resistance, at the end of one second a bullet fired straight up into the air will have traveled a distance of A) (100 - 4.9) m. B) (100 + 4.9) m. C) 100 m. D) 4.9 m. E) none of these.
C
46) Someone standing at the edge of a cliff throws one ball straight up and another ball straight down at the same initial speed. Neglecting air resistance, the ball to hit the ground below the cliff with the greater speed will be A) the one thrown upward. B) the one thrown downward. C) neither - they will both hit with the same speed.
A
47) A ball is thrown upwards. Neglecting air resistance, what initial upward speed does the ball need to remain in the air for a total time of 10 seconds? A) about 50 m/s B) about 60 m/s C) about 80 m/s D) about 100 m/s E) about 110 m/s
B
48) A ball is thrown 125 meters upward and then falls the same distance back to Earth. Neglecting air resistance, its total time in the air is about A) 5 seconds. B) 10 seconds. C) 15 seconds. D) more than 20 seconds.
A
49) A pot falls from a ledge and hits the ground 45 m below. The speed with which it hits the ground is about A) 30 m/s. B) 60 m/s. C) 120 m/s. D) more than 120 m/s.
In its first second of free fall, a dropped softball will fall a vertical distance of
5 m
B
5) The average speed of a horse that gallops a distance of 10 kilometers in a time of 30 minutes is A) 10 km/h. B) 20 km/h. C) 30 km/h. D) more than 30 km/h.
B
51) A man leans over the edge of a cliff and throws a rock upward at 4.9 m/s. Neglecting air resistance, one second later the rock's speed is A) zero. B) 4.9 m/s. C) 9.8 m/s. D) 14.7 m/s. E) none of the above.
D
52) A man leans over the edge of a cliff and throws a rock upward at 4.9 m/s. Neglecting air resistance, two seconds later the rock's speed is A) zero. B) 4.9 m/s. C) 9.8 m/s. D) 14.7 m/s. E) none of the above.
B
53) A man leans over the edge of a cliff and throws a rock upward at 4.9 m/s. How far below the level from which it was thrown is the rock 2 seconds later? A) 4.9 m B) 9.8 m C) 14.7 m D) 19.6 m
Jogging Jake runs at 4 m/s along a train flatcar that moves at 10 m/s in the opposite direction. Jake's speed relative to the ground is
6 m/s
A car's speed 3 seconds after accelerating from rest at 2 m/s2 is
6 m/s.
If a car increases its velocity from zero to 60 m/s in 10 seconds, its acceleration is
6 m/s^2
A
6) What is the acceleration of a car that maintains a constant velocity of 100 km/hr for 10 seconds? A) 0 B) 10 km/hr s C) 10 m/hr s D) 1000 km/hr s
At one instant an object in free fall is moving downward at 50 m/s. One second later its speed is
60 m/s.
You are not moving relative to the chair, but you are moving over 100,000 km/h relative to the Sun.
As you read this in your chair, how fast are you moving relative to the chair? Relative to the Sun?
Which BEST describes what occurs when a body accelerates?
Change in velocity per unit time.
Why does the distance traveled by the ball in each half second after it is released change in the way that it does?
Gravity is pulling down on the ball, so it accelerates down at a steady rate.
As the angle of the inclined plane increases, how does the final speed attained by the ball at the bottom of the inclined plane change?
It increases.
How does the acceleration of the ball change as the angle of the inclined plane increases?
It increases.
How does the distance traveled by the ball in the second half second compare with the distance traveled by the ball in the first half second?
It increases.
Why does the final speed attained by the ball at the bottom of the inclined plane change in the way that it does when the angle of the incline plane increases?
The ball accelerates at a greater rate for the same duration of time.
If a car is moving at 90 km/h and it rounds a corner, also at 90 km/h, does it maintain a constant speed? A constant velocity? If a car is moving at 90 km/h and it rounds a corner, also at 90 km/h, does it maintain a constant speed? A constant velocity?
It maintains a constant speed, but does not maintain a constant velocity.
Phil Physiker standing at the edge of a cliff throws one ball straight up and another ball straight down, both with the same speed. Neglecting air resistance, which ball hits the ground below with the greater speed?
Neither, both hit with the same speed.
