Sharon

A dog and a cat are running straight towards each other. The dog is going 2.5 m/s and has a mass of 5 kg. The cat is going 1.1 m/s and has a mass of 1.3 kg. Assume the dog is running initially with a positive velocity. The two animals collide. After the collision, if the dog bounces backward at 1.4 m/s, then the cat's speed must be

A child and sled with a combined mass of 48.1

kg slide down a frictionless hill that is 8.01 m

high at an angle of 19 ◦ from horizontal. The acceleration of gravity is 9.81 m/s ^2. If the sled starts from rest, what is its speed 

at the bottom of the hill?

Answer in units of m/s.

A pendulum bob is released from some initial

height such that the speed of the bob at the

bottom of the swing is 1.9 m/s. The acceleration of 

gravity is 9.81 m/s ^2. What is the initial height of the bob? 

Answer in units of m.

A bird is flying with a speed of 16.6 m/s over

water when it accidentally drops a 2.10 kg

fish. The acceleration of gravity is 9.81 m/s 2 

.If the altitude of the bird is 7.20 m and air 

resistance is disregarded, what is the speed of

the fish when it hits the water?

Answer in units of m/s.

Tim, with mass 78.1 kg, climbs a gymnasium

rope a distance of 4.7 m.

The acceleration of gravity is 9.8 m/s ^2.

How much potential energy does Tim gain? 

Answer in units of J.

An automobile engine delivers 41.4 hp.

How much time will it take for the engine

to do 5.26 × 10^5 J of work? One horsepower 

is equal to 746 watts. Answer in units of s. 

A 1.03×103kg car accelerates uniformly from rest to 12.7 m/s in 2.80s.What is the work done on the car in this time interval?  Answer in units of J.

2. What is the power delivered by the engine in

this time interval?

Answer in units of W.

A student weighing 729 N climbs at constant

speed to the top of an 8 m vertical rope in

13 s. What is the average power expended by the 

student to overcome gravity?

Answer in units of W.

Lee pushes horizontally with a force of 67 N

on a 10 kg mass for 25 m across a floor.

Calculate the amount of work Lee did.

Answer in units of J.

The amount of work done by two boys who

apply 180 N of force in an unsuccessful attempt to move a stalled car is

1. 360 N.

2. 360 N · m.

3. 180 N · m.

4. 180 N.

5. 0

Shawn and his bike have a total mass of 58.7 kg. Shawn rides his bike 0.98 km in 10.7 min at a constant velocity. The acceleration of gravity is 9.8 m/s^2What is Shawn’s kinetic energy?  Answer in units of J.

2. What is the speed of a 0.150 kg baseball if its

kinetic energy is 107 J ?

A car with a mass of 1990 kg kg starts from

rest and accelerates to a speed of 11.5 m/s in 18.4 s. Assume that the force of resistance remains constant at 331.4 N during this time. 

What is the average power developed by the car’s engine?  Answer in units of W

A small air compressor operates on a 2.3 hp

(horsepower) electric motor for 9.3 hours a

day. How much energy is consumed by the motor 

daily? 1 hp equals about 750 watts. Answer in units of J.

If electricity costs 30 cents per kilowatt-hour,

how much does it cost to run the compressor

each day?

Answer in units of cents.

A tugboat pulls a ship with a constant net

horizontal force of 4.93 × 103 N and causes

the ship to move through a harbor.

How much work does the tugboat do on the

ship if each moves a distance of 4.49 km ?

Answer in units of J.

A tugboat pulls a ship with a constant net

horizontal force of 5.02 × 103 N and causes

the ship to move through a harbor.

How much work does the tugboat do on the

ship if each moves a distance of 4.12 km ?

Answer in units of J.

A car with a mass of 1390 kg kg starts from

rest and accelerates to a speed of 18.5 m/s in 18.1 s. Assume that the force of resistance remains constant at 495.9 N during this time. What is the average power developed by the car’s engine? Answer in units of W.

A small air compressor operates on a 2.9 hp (horsepower) electric motor for 4.9 hours a day. How much energy is consumed by the motor daily? 1 hp equals about 750 watts. Answer in units of J. 

2. If electricity costs 22 cents per kilowatt-hour,

how much does it cost to run the compressor

each day?

Answer in units of cents.

A student weighing 727 N climbs at constant speed to the top of an 14 m vertical rope in 19 s. What is the average power expended by the student to overcome gravity Answer in units of W

A tugboat pulls a ship with a constant net horizontal force of 5.51 × 103 N and causes the ship to move through a harbor. How much work does the tugboat do on the 

ship if each moves a distance of 3.48 km ? Answer in units of J