
 Physical Science, 5/e Bill Tillery,
Arizona State University
Energy
Exercises A force of 200 N is needed to push a table across a level classroom floor for a distance of 3 m. How much work was done on the table?Answer
 An 880 N box is pushed across a level floor for a distance of 5.0 m with a force of 440 N. How much work was done on the box?Answer
 How much work is done in raising a 10.0 kg backpack from the floor to a shelf 1.5 m above the floor?Answer
 If 5,000 J of work is used to raise a 102 kg crate to a shelf in a warehouse, how high was the crate raised?Answer
 A 60.0 kg student runs up a 5.00 meter high stairway in a time of 3.92 seconds. (a) How many watts of power did she develop?Answer (b) How many horsepower is this?Answer
 (a) How many horsepower is a 1,400 W blow dryer?Answer (b) How many watts is a 3.5 hp lawnmower?Answer
 What is the kinetic energy of a 2,000 kg car moving at 72 km/hr?Answer
 How much work is needed to stop a 1,000.0 kg car that is moving straight down the highway at 54.0 km/hr?Answer
 A horizontal force of 10.0 lb is needed to push a bookcase 5 ft across the floor. (a) How much work was done on the bookcase?Answer (b) How much did the gravitational potential energy change as a result?Answer
 (a) How much work is done in moving a 2.0 kg book to a shelf 2.00 m high?Answer (b) What is the potential energy of the book as a result?Answer (c) How much kinetic energy will the book have as it hits the ground as it falls?Answer
 A 150 g baseball has a velocity of 30.0 m/s. What is its kinetic energy in J?Answer
 (a) What is the kinetic energy of a 1,000.0 kg car that is traveling at 90.0 km/hr?Answer (b) How much work was done to give the car this kinetic energy?Answer (c) How much work must be done to now stop the car?Answer
 A 60.0 kg jogger moving at 2.0 m/s decides to double the jogging speed. How did this change in speed change the kinetic energy?Answer
 A bicycle and rider have a combined mass of 70.0 kg and are moving at 6.00 m/s. A 70.0 kg person is now given a ride on the bicycle. (Total mass is 140.0 kg.) How did the addition of the new rider change the kinetic energy at the same speed?Answer
 A 170.0 lb student runs up a stairway to a classroom 25.0 ft above ground level in 10.0 s. (a) How much work did the student do?Answer (b) What was the average power output in hp?Answer
 (a) How many seconds will it take a 20.0 hp motor to lift a 2,000.0 lb elevator a distance of 20.0 ft?Answer (b) What was the average velocity of the elevator?Answer
 A ball is dropped from 9.8 ft above the ground. Using energy considerations only, find the velocity of the ball just as it hits the ground.Answer
 What is the velocity of a 1,000.0 kg car if its kinetic energy is 200 kJ?Answer
 A Foucault pendulum swings to 3.0 in above the ground at the highest points and is practically touching the ground at the lowest point. What is the maximum velocity of the pendulum?Answer
 An electric hoist is used to lift a 250.0 kg load to a height of 80.0 m in 39.2 s. (a) What is the power of the hoist motor in kW?Answer (b) in hp?Answer


