Physics Chapter 4

An apple falls from a tree and hits the ground 5 meters below. It hits the ground with a speed of about

10 m/s

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

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

A car accelerates at 2 meters/s/s. Assuming the car starts from rest, how far will it travel in 10 s

100 m

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

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

250 m

While a car travels around a circular track at a constant speed, its

None of the above

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

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 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

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

4.0

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

A car maintains a constant velocity of 100 km/hr for 10 seconds. During this interval its acceleration is

Zero

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

If a rocket initially at rest accelerates at a rate of 50 m/s2 for one minute, its speed will be

3000 m/s

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

4

Distance fallen in 1 second from rest

5m by using d=1/2g(t)²

If a car increases its velocity from zero to 60 km/h in 10 seconds, its acceleration is

6 km/h/s

If a car accelerates from rest at 2 meters per second, its speed 3 seconds later will be about

6 m/s

At one instant an object in free fall is moving downward at 50 meters per second. One second later its speed should be about

60 m/s

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

In each second of fall, the distance a freely falling object will fall is

increasing

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 9.8

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 car accelerates at 2 meters per second. Assuming the car starts from rest, how much time does it need to accelerate to a speed of 30 m/s

15 seconds

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

A horse gallops a distance of 10 kilometers in a time of 30 minutes. Its average speed is

20 km/h

One half second after starting from rest, a freely falling object will have a speed of about

5 m/s

Relative Motion

All motion is relative to the observer and the reference point used.

Vector quantity

Quantity in physics that has both magnitude and direction.

Instantaneous speed

Speed at any instant.

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 10 seconds

It takes 6 seconds for a stone to fall to the bottom of a mine shaft. How deep is the shaft

about 180 m

It takes 6 seconds for a stone to fall to the bottom of a mine shaft. How deep is the shaft?

about 180 m

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

about 50 m/s

Disregarding air resistance, objects fall with constant

acceleration

If an object moves with constant acceleration, its velocity must

change by the same amount each second

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

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

is the same for each bullet

Twelve seconds after starting from rest, an object falling freely will have a speed of

more than 100 m/s

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

neither -- they will both hit with the same speed

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

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

the same amount

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

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

zero