 # The two measurements necessary for calculating average speed are

## Presentation on theme: "The two measurements necessary for calculating average speed are"— Presentation transcript:

The two measurements necessary for calculating average speed are
3.1 Questions About Linear Motion 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.

2) A horse gallops a distance of 10 kilometers in a time of 30 minutes. Its average speed is A) 15 km/h. B) 20 km/h. C) 30 km/h. D) 40 km/h.

3) A car maintains a constant velocity of 100 km/hr for 10 seconds. During this interval its acceleration is A) zero. B) 10 km/hr. C) 110 km/hr. D) 1000 km/hr.

4) While an object near the Earth's surface is in free fall, its
3.1 Questions About Linear Motion 4) While an object near the Earth's surface is in free fall, its A) velocity increases. B) acceleration increases. C) mass increases. D) mass decreases.

C) equal to its weight divided by its mass.
3.1 Questions About Linear Motion 5) 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. B) equal to its weight. C) equal to its weight divided by its mass. D) equal to the product of its mass times its weight.

6) 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 A) 10 m/s. B) 20 m/s. C) 30 m/s. D) 40 m/s.

B) less and less each second. C) greater than the second before.
3.1 Questions About Linear Motion 7) 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 A) constant. B) less and less each second. C) greater than the second before. D) doubled.

E) depends on its initial speed
3.1 Questions About Motion 8) If a freely falling object were somehow equipped with a speedometer, its speed reading would increase each second by about A) 5 m/s. B) 10 m/s. C) 15 m/s. D) a variable amount. E) depends on its initial speed

E) depends on its initial speed
3.1 Questions About Motion 9) 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 A) 10 m/s. B) 20 m/s. C) 30 m/s. D) 40 m/s. E) depends on its initial speed

10) Twelve seconds after starting from rest, an object falling freely will have a speed of A) 10 m/s. B) 50 m/s. C) 100 m/s. D) more than 100 m/s.

11) If an object moves with constant acceleration, its velocity must
3.1 Questions About Motion 11) If an object moves with constant acceleration, its velocity must A) be constant also. B) change by the same amount each second. C) change by varying amounts depending on its speed. D) always decrease.

12) 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.

13) 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. Answer: C

E) not enough information given to estimate Answer: B
3.1 Questions About Motion 14) 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 Answer: B

15) 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 Answer: C

16) 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 Answer: D

17) A car accelerates at 2 meters/s/s. Assuming the car starts from rest, how far will it travel in 10 s? A) 2 m B) 10 m C) 40 m D) 100 m E) 200 m Answer: D

18) 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 about A) half as much. B) the same amount. C) twice as much. D) four times as much. Answer: B

A) in the direction of motion. B) opposite its velocity.
3.1 Questions About Motion 19) 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. Answer: D

A) acceleration is zero. B) velocity is zero. C) inertia is zero.
3.1 Questions About Motion 20) While a car travels around a circular track at a constant speed, its A) acceleration is zero. B) velocity is zero. C) inertia is zero. D) none of the above Answer: D

21) If a car accelerates from rest at 2 meters per second per second, its speed 3 seconds later will be about A) 2 m/s. B) 3 m/s. C) 4 m/s. D) 6 m/s. Answer: D

22) 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 A) half as much. B) the same. C) twice as much. D) four times as much. Answer: B

23) 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 A) 0. B) 5. C) 8. D) 24. Answer: A

24) At one instant an object in free fall is moving downward at 50 meters per second. One second later its speed should be about A) 25 m/s. B) 50 m/s. C) 55 m/s. D) 60 m/s. E) 100 m/s. Answer: D

25) At one instant a heavy object in air is moving upward at 50 meters per second. One second later its speed is approximately A) 40 m/s. B) 50 m/s. C) 55 m/s. D) 60 m/s. Answer: A

26) Disregarding air resistance, objects fall with constant
3.1 Questions About Motion 26) Disregarding air resistance, objects fall with constant A) velocity. B) speed. C) acceleration. D) distances each successive second. Answer: C

A) more than the speed it had when thrown upwards.
3.1 Questions About Motion 27) 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 always 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. D) impossible to determine. Answer: B

28) Starting from rest, the distance a freely falling object will fall in 0.5 second is about A) 1 m. B) 10 m. C) 1.00 m. D) none of the above Answer: D

29) 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 Answer: C

30) 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. Answer: E

31) An object falls freely from rest on a planet where the acceleration due to gravity is twice as much as it is on Earth. 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 Answer: C

E) not enough information given to estimate Answer: B
3.1 Questions About Motion 32) 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 Answer: B

33) 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 Answer: C

A) less than 9.8 meters per second per second.
3.1 Questions About Motion 34) 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. Answer: B

35) 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

D) not enough information to estimate Answer: A
3.1 Questions About Motion 36) 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 Answer: A

3.1 Questions About Motion 37) 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 Answer: B Answer: A

C) remain at a relatively fixed distance from one another. Answer: B
3.1 Questions About Motion 38) Consider drops of water that leak at a steady rate 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. Answer: B

39) 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 Answer: C

40) 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 Answer: B

41) 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 Answer: D

42) 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 Answer: C

A) velocity is zero and its acceleration is zero.
3.1 Questions About Motion 43) 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 Answer: B

A) the fired bullet is greater. B) the dropped bullet is greater.
3.1 Questions About Motion 44) 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. Answer: C

45) 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 A) ( ) m. B) ( ) m. C) 100 m. D) 4.9 m. E) none of these Answer: A

D) depends on the height of the cliff. Answer: B
3.1 Questions About Motion 46) 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 A) is less than 9.8. B) is 9.8. C) is more than 9.8. D) depends on the height of the cliff. Answer: B

A) is greater for the dropped bullet.
3.1 Questions About Motion 47) 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 Answer: C

A) the one thrown upward. B) the one thrown downward.
3.1 Questions About Motion 48) 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. Answer: C

49) 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 Answer: A

50) 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 A) about 5 seconds. B) about 10 seconds. C) about 15 seconds. D) more than 20 seconds. Answer: B

51) A pot falls from a ledge and hits the ground 45 m below. The speed with which it hits the ground is A) about 30 m/s. B) about 60 m/s. C) about 120 m/s. D) more than 120 m/s. Answer: A

53) 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 Answer: B