Physics Chapter 3

A football is kicked at an angle, giving it a horizontal velocity of 25 m/s. At the highest point in its path, the football will have a velocity of ________ m/s and a horizontal acceleration of ___________ m/s2.

25 and zero

A ball is projected upward with an initial velocity of 10 m/s. It will reach its maximum height in approximately A. 1 s. B. 1.5 s. C. 2 s. D. 2.5 s. E. 3 s.

A. 1 s.

A freely falling object (neglecting air resistance) has its velocity A. increase linearly with time. B. remain constant. C. decreases linearly with time. D. increase as the square of the time.

A. increase linearly with time.

A bullet is fired straight down from a hovering helicopter. If we neglect air friction, then the speed of the bullet A. increases at 9.8 m/s each second. B. is a constant. C. is zero. D. decreases at 9.8 ft/s during the flight.

A. increases at 9.8 m/s each second.

Which of the curves in the figure best shows the speed of an object falling from rest without air friction? A B C

B

In order to find the depth of a well, you drop a stone into it and time its fall. It hits the water after falling for 1.5 s. The depth of the well is about A. 7.35 m. B. 11 m. C. 14 m. D. 20 m.

B. 11 m.

A 10 pound iron ball and a 2 pound iron ball are dropped simultaneously from a height of 100 meters. Neglecting air resistance, which ball will reach the ground first? A. The 10 lb ball B. The 2 lb ball C. They will reach the ground at the same time

C. They will reach the ground at the same time

Two identical pieces of paper, one crumpled into a ball and the other left uncrumpled, are released simultaneously from inside the top of a large evacuated tube. Which one, if either, do you expect to reach the floor first? A. the crumpled paper B. the uncrumpled paper C. both will reach the floor at the same time

C. both will reach the floor at the same time

A ball is thrown at an angle above the horizontal. The horizontal speed of the ball is 20 m/s and the ball covers a distance of 10 m. The maximum height of the arc through which the ball travels is A. 1.2 m. B. 4.9 m. C. 10 m. D. 0.31 m

D. 0.31 m

Assuming g = 10 m/s2 and that air resistance is negligible, in 1/2 second a ball dropped from rest will fall A. 0.3 m. B. 0.8 m. C. 1.0 m. D. 1.25 m. E. 2.25 m.

D. 1.25 m.

The diagram shows the positions at intervals of 0.05 seconds of two balls moving from left to right. Which of the statements about the acceleration of the balls is correct? A. ball A is accelerating leftwards, ball B is accelerating leftwards B. ball A is accelerating rightwards, ball B is accelerating rightwards C. ball A is accelerating leftwards, ball B is accelerating rightwards D. ball A is accelerating rightwards, ball B is accelerating leftwards E. neither ball is accelerating

D. ball A is accelerating rightwards, ball B is accelerating leftwards

The motion of a falling object is commonly investigated with the aid of a A. stethoscope. B. microscope. C. kaleidoscope. D. stroboscope.

D. stroboscope.

For a bullet fired horizontally, its ___________ velocity will retain a constant non-zero value until it is stopped.

horizontal

A ___________ is a body whose only acceleration is the downward acceleration due to gravity.

projectile

The diagram shows a wastebasket placed behind a chair. Three different directions are indicated for the velocity of a ball thrown by the kneeling woman. Which of the three directions is most likely to result in the ball landing in the basket? A B C

A

Which of these graphs would be correct for the speed of a ball thrown upward? A D C B

A

A ball is thrown straight up with an initial velocity of 10 m/s. After 3 seconds its velocity will be A. -19.4 m/s. B. -29.4 m/s. C. 0 m/s. D. 29.4 m/s. E. 19.4 m/s.

A. -19.4 m/s.

If cars are traveling on a highway at constant speed what is the advantage, if any, of remaining more than a car length behind the car in front of you? A. reducing the chance of rear-end collision B. allowing for large acceleration towards to car in front of you C. reducing the chance a car cuts into your lane

A. reducing the chance of rear end collisions

Two identical pieces of paper, one crumpled into a ball and the other left uncrumpled, are released simultaneously from the same height above the floor. Which one, if either, do you expect to reach the floor first? A. the crumpled paper B. the uncrumpled paper C. both will reach the floor at the same time

A. the crumpled paper

A football quarterback must hit a moving target while eluding onrushing linemen. What is an advantage a hard low-trajectory? A. the defense has less time to react to the throw B. the receiver has more time to adjust his position C. a lighter throw is needed by the quarterback

A. the defense has less time to react to the throw

A ball rolls off a shelf and hits the floor below 0.25 seconds later. To find the speed of the ball as it left the shelf, we would need A. the distance measured along the floor to the point of impact. B. to repeat the experiment. C. the height of the table.Incorrect D. the weight of the ball.

A. the distance measured along the floor to the point of impact.

In the diagram, two different trajectories are shown for a ball thrown by a center fielder to home plate in a baseball game. Which of the two trajectories (if either) will result in the longer time? A. the higher trajectory B. the lower trajectory C. both will take the same time to arrive at home plate

A. the higher trajectory

Aristotle stated that heavier objects fall faster than lighter objects. Is there a sense in which Aristotle's view could be considered correct? A. when objects have hit terminal velocity B. before objects hit terminal velocity C. no, Aristotle was not correct at all

A. when objects have hit terminal velocity

For identical cannons and identical projectiles and identical initial speeds, but different pointing angles, the maximum distance for its projectile is attained for the cannon which launches at A. 32° above horizontal. B. 45° above horizontal. C. either 32° or 58° above horizontal. D. zero degrees—a flat trajectory.

B. 45° above horizontal.

An iron robot falls from rest at a great height. Neglecting air resistance, what distance has it fallen in the first 3.5 seconds? A. 31 m B. 60 m C. 49 m D. 98 m

B. 60 m

Which of the three curves show the speed of an object that is beginning to experience significant air resistance? A. Object U B. Object G C. Object K

B. Object G

A body released from rest falls with an acceleration of 9.8 m/s2. If the same body is thrown upward at an angle, and air resistance is negligible, its acceleration after release will be A. downward and less than 9.8 m/s2. B. downward and equal to 9.8 m/s2. C. downward and greater than 9.8 m/s2. D. upward and equal to 9.8 m/s2. E. upward and greater than 9.8 m/s2.

B. downward and equal to 9.8 m/s2.

A ball is thrown straight upwards. At the very top of its flight, the velocity of the ball is zero. What direction, if any, is the acceleration at this point? A. upwards B. downwards C. the acceleration is zero

B. downwards

If you drop a ball in the absence of air resistance, it accelerates downward at 9.8 m/s2. If instead, you throw the ball upward, then its downward acceleration after release is A. less than 9.8 m/s2. B. equal to 9.8 m/s2. C. greater than 9.8 m/s2.

B. equal to 9.8 m/s^2

Just after it is released, an object thrown upward has A. its velocity directed upward and its acceleration directed upward. B. its velocity directed upward and its acceleration directed downward. C. its velocity directed downward and its acceleration directed upward. D. its velocity directed downward and its acceleration directed downward.

B. its velocity directed upward and its acceleration directed downward.

Just before it reaches the peak of the path of its motion, an object thrown upward has A. its velocity directed upward and its acceleration directed upward. B. its velocity directed upward and its acceleration directed downward. C. its velocity directed downward and its acceleration directed upward. D. its velocity directed downward and its acceleration directed downward.

B. its velocity directed upward and its acceleration directed downward.

Will a shot fired from a cannonball at a 20° launch angle travel for a longer distance than a 45° shot? A. yes, the 20° will go further B. no, the 45° will go further C. both will go the same distance

B. no, the 45° will go further

A cannonball fired from a cannon at an angle of 70° to the horizontal stays in the air longer than one fired at 45° from the same cannon. Which shot will travel the furthest distance? A. the 70° cannon shot B. the 45° cannon shot C. both will travel the same distance

B. the 45° cannon shot

The acceleration due to gravity near the surface of the Moon is about one-sixth of the value near the Earth's surface. If a rock were dropped from equal heights on the Moon and Earth, the time it would take the rock from the Moon to hit the ground would be A. six times longer than on Earth.Incorrect B. the square root of six times longer than on Earth. C. the same time as on Earth. D. the square root of six times shorter than on Earth. E. six times shorter than on Earth.

B. the square root of six times longer than on Earth.

A ball thrown straight upwards moves initially with decreasing upward velocity. What are the directions of the velocity and acceleration vectors during this part of the motion? A. the velocity vector is upwards, the acceleration vector is upwards B. the velocity vector is upwards, the acceleration vector is downwards C. the velocity vector is downwards, the acceleration vector is upwards D. the velocity vector is downwards, the acceleration vector is downwards

B. the velocity vector is upwards, the acceleration vector is downwards

During the first 5 seconds after a ball is dropped from rest, how far will it fall? A. 25 m B. 61.3 m C. 122.5 m D. 245 m E. 490 m

C. 122.5 m

To get a clean "swish"—nothing but net—on the basketball floor, you must shoot the ball so that its velocity vector is at least ________ above horizontal when it gets to the hoop. A. 45° B. 58° C. 32° D. 30°

C. 32°

After 1 second, a ball dropped from rest will have fallen A. 1.0 m. B. 2.45 m. C. 4.9 m. D. 9.8 m.

C. 4.9 m.

A ball is thrown straight up. It reaches its highest point and then falls back. Which of the following is the correct statement? A. Throughout its motion, the ball's velocity is zero B. At the highest point in its motion, the ball's acceleration is zero C. At the highest point in its motion, the ball's velocity is zero D. Throughout its motion, the ball's acceleration is zero E. At the highest point in its motion, the ball's velocity and acceleration are zero

C. At the highest point in its motion, the ball's velocity is zero

A rifle bullet is fired horizontally at the same instant another bullet is allowed to drop from rest at the same height. Which bullet strikes the earth first? A. The bullet from the rifle B. The bullet allowed to drop C. Both strike at the same instant

C. Both strike at the same instant

A person standing at the edge of a cliff throws one rock straight up and another rock straight down at the same initial speed. The rock that was thrown __________ has less speed at impact. A. upward B. downward C. Each rock has the same speed just before impact

C. Each rock has the same speed just before impact

Two projectiles are launched 50° above horizontal but with different initial speeds. Which of the following must be true while the projectiles are in the air? (Ignore air resistance.) A. The projectiles will reach the same maximum height B. The horizontal speeds of both projectiles are the same C. The horizontal accelerations of both projectiles are the same: zero D. The one with larger initial speed will experience a larger vertical acceleration

C. The horizontal accelerations of both projectiles are the same: zero

Neglecting friction, if a Cadillac and Volkswagen start rolling down a hill together, the heavier Cadillac will get to the bottom A. before the Volkswagen. B. after the Volkswagen. C. at the same time as the Volkswagen.

C. at the same time as the Volkswagen.

A lead ball and an aluminum ball, each 1 in. in diameter, are released simultaneously and allowed to fall to the ground. Due to its greater density, the lead ball has a substantially larger mass than the aluminum ball. Which of these balls, if either, has the greater acceleration due to gravity? A. the lead ball B the aluminum ball C. both balls have the same acceleration due to gravity

C. both balls have the same acceleration due to gravity

A ball rolling rapidly along a tabletop rolls off the edge and falls to the floor. At the exact instant that the first ball rolls off the edge, a second ball is dropped from the same height. Which ball, if either, reaches the floor first? A. the dropped ball B. the rolling ball C. both balls reach the floor at the same time

C. both balls reach the floor at the same time

A red ball is thrown downwards with a large starting velocity. A blue ball is dropped from rest at the same time as the red ball. Which ball accelerate will experience the largest acceleration during the fall? A. the blue ball B. the red ball C. both balls will have the same acceleration D. it is impossible to determine without the mass of the balls

C. both balls will have the same acceleration

During every second after an object is dropped from rest and experiences free fall, its speed A. decreases by approximately 5 m/s. B. increases by approximately 5 m/s. C. increases by approximately 10 m/s. D. decreases by approximately 10 m/s.

C. increases by approximately 10 m/s.

A ball rolls up an inclined plane, slows to a stop and then rolls back down. Which of the following statements about the acceleration of the ball is correct? A. the acceleration changes from up the incline to down the incline B. the acceleration changes from down the incline to up the incline C. the acceleration remains constant and downwards along the incline D. the acceleration remains constant and upwards along the incline

C. the acceleration remains constant and downwards along the incline

The diagram shows the positions at intervals of 0.10 seconds of a ball moving from left to right (as in a photograph taken with a stroboscope that flashes every tenth of a second). In what direction, if any, is the ball accelerated? A. leftwards B. rightwards C. the ball is not accelerated

C. the ball is not accelerated

In shooting a free throw in basketball, what is the primary advantage that a high, arching shot has over one with a flatter trajectory? A. the higher arched shot is traveling faster horizontally B. the higher arched shot is traveling faster vertically C. the higher arched shot has a larger range of successful trajectories

C. the higher arched shot has a larger range of successful trajectories

A ball is thrown across the street. During its flight, the ball's speed is lowest at A. the beginning of its flight. B. the end of its flight. C. the highest point of its flight. D. The speed is constant throughout the flight

C. the highest point of its flight.

You toss a ball straight up in the air. At the highest point, the ball's A. velocity and acceleration are zero. B. acceleration is zero but not its velocity. C. velocity is zero and the acceleration is downward. D. velocity is zero and the acceleration is upward.

C. velocity is zero and the acceleration is downward.

A rock is thrown straight upwards reaching a height of 20 meters. In which segment of its flight does it spend the most time? A. the bottom 5 meters B. the middle 5 meters C. the top 5 meters D. the time it spends is equal during all distance intervals

C.the top 5 meters

Suppose you throw a ball vertically downward with a speed of 10 m/s. Neglecting air friction, what would be the speed of the ball one second later? A. -9.8 m/s2 B. 9.8 m/s2 C. 15 m/s D. 19.8 m/s E. 24.8 m/s

D. 19.8 m/s

An iron robot falls from rest at a great height. Neglecting air resistance, what is its speed after it has fallen for 3.5 seconds? A. 9.8 m/s B. 9.8 m/s2 C. 13.3 m/s D. 34.3 m/s

D. 34.3 m/s

A stone is thrown upward from a bridge at a speed of 10 m/s. It narrowly misses the bridge on the way back down and hits the water at 30 m/s. The bridge is about A. 3 m high. B. 20 m high. D. 50.5 m high. D. 40.8 m high.

D. 40.8 m high.

In a laboratory on Earth, all the air is pumped from a large tube. A feather and a steel ball are simultaneously released from rest inside the tube. What happens next? A. Both objects float weightlessly inside the tube B. The steel ball falls and hits the bottom before the feather C. The feather falls and hits the bottom before the steel ball D. Both objects fall and hit the bottom at the same time

D. Both objects fall and hit the bottom at the same time

A football is thrown upward at some angle above the horizontal. If we neglect air friction, then we can conclude that the acceleration vector of the football is A. opposite to the velocity vector. B. zero. C. along the direction of motion. D. down.

D. down.

An object is thrown upward at 5.0 m/s, and experiences only the force of gravity once thrown. One second later the object is A. rising at 4.8 m/s. B. rising at 5 m/s. C. neither rising nor falling. D. falling at 4.8 m/s.

D. falling at 4.8 m/s.

A ball is thrown straight upwards and then returns to the Earth. How does the acceleration vector change during this motion? A. it goes from pointing downwards to upwards B. it goes from pointing upwards to downwards C. it remains upwards the entire time D. it remains downwards the entire time

D. it remains downwards the entire time

A ball thrown straight upwards moves initially with decreasing upward velocity. What happens to the acceleration vector during this time? A. it is zero B. it is increasing C. it is decreasing D. it remains the same size

D. it remains the same size

After it passes the peak of the path of its motion, an object thrown upward has A. its velocity directed upward and its acceleration directed upward. B. its velocity directed upward and its acceleration directed downward. C. its velocity directed downward and its acceleration directed upward. D. its velocity directed downward and its acceleration directed downward.

D. its velocity directed downward and its acceleration directed downward.

(Ignore air resistance for this problem.) Two identical balls are thrown simultaneously from the top of a very tall cliff. Ball A is thrown downward with an initial velocity of 6 m/s, while ball B is thrown straight upward with an initial velocity of 9.8 m/s. After one second has elapsed, the A. acceleration of ball A is upward. B. velocity of ball A is 9.8 m/sec2. C. acceleration of ball A is greater than that of ball B. D. velocity of ball B is zero. E. acceleration of both balls is zero.

D. velocity of ball B is zero.

The acceleration of a body is given by the slope of a graph plotting A. distance travelled versus time. B. time versus velocity. C. velocity versus distance travelled. D. velocity versus time. E. time versus distance travelled.

D. velocity versus time.

The acceleration due to gravity near the surface of Mars is about one-third of the value near the Earth's surface. If a rock fell from rest for the same amount of time on Mars and Earth, the final speed of the rock would be A. three times faster than on Earth. B. the square root of three times faster than on Earth. C. the same speed as on Earth. D. the square root of three times slower than on Earth. E. three times slower than on Earth.

E. three times slower than on Earth.

Is it possible for an object to have a horizontal component of velocity that is constant at the same time that the object is accelerating in the vertical direction?

Yes

The diagram shows a wastebasket placed behind a chair. Three different directions are indicated for the velocity of a ball thrown by the kneeling woman. Is the magnitude of the velocity important to the success of the shot?

Yes

A body whose velocity increases by a constant amount each second is exhibiting motion for which the ____________________ is constant.

acceleration