The Physical World: Chapter 3-4

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

0

When a falling object has reached its terminal velocity, its acceleration is

0

Calculate the speed of a bowling ball that travels 4.6 meters in 2.4 seconds.

1.9 m/s

A skydiver steps from a high-flying helicopter. In the absence of air resistance, how fast would she be falling at the end of a 12-s jump?

120 m/s

You toss a ball straight up with an initial speed of 20m/s . How high does it go?

20 m

Calculate the acceleration of a ball that starts from rest, rolls down a ramp, and gains a speed of 23m/s in 6.0 seconds.

3.8 m/s^2

A grocery bag can withstand 300 N of force before it rips apart. How many kilograms of apples can it safely hold?

30.6 kg

You toss a ball straight up with an initial speed of 20m/s . How long is it in the air (neglecting air resistance)?

4.0 s

Calculate the distance (in km) that Larry runs if he maintains an average speed of 9.1km/h for 1 hour.

9.1 km/h

If an object moves with constant acceleration, its velocity must: always decrease. be constant also. change by the same amount each second. change by varying amounts depending on its speed

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. directed upward. opposite its velocity. in the direction of motion.

Directed downward

The newton is a unit of:

Force

The vertical height attained by a basketball player who achieves a hang time of a full 1 s is: about 1.2 m. more than 2.5 m. about 0.8 m. about 2.5 m. about 1 m.

about 1.2 m

It takes 6 seconds for a stone to fall to the bottom of a mine shaft. How deep is the shaft? about 120 m more than 200 m about 60 m about 180 m

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 100 m/s about 60 m/s about 110 m/s about 80 m/s about 50 m/s

about 50 m/s

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

more than 100 m/s

Two factors that greatly affect air resistance on falling objects are the

size and speed of the object

Your weight is: a property of mechanical equilibrium. the gravitational attraction force between you and the Earth. equal to your mass. all of these

the gravitational attraction between you and the Earth

Strange as it may seem, it is just as hard to accelerate a car on a level surface on the moon as it is here on the Earth. This is because: the mass of the car is independent of gravity. the weight of the car is independent of gravity. Nonsense! A car is much more easily accelerated on the moon than on the Earth.

the mass of the car is independent of gravity