INTRODUCTORY WORK QUESTIONS

  1. A constant force of 30.0N is required to slide a 20.0 kg table across a floor a distance of 15.0 metres. Calculate the amount of work done in overcoming friction during this process.
  1. If the 25.0N force acts for a distance of 8.40 metres, how much work is done?

3. A 60.0 kg boy pushes a 50.0 kg girl around a dance floor. He exerts an average force of 80.0N on his partner. During the dance they move at a rate of 0.50 m/s for 5.00 minutes.

a.)How far do they move?

b.)How much work does the poor boy do?

4. How much work is done by a person who takes a 7.5kg gym bag from the floor and sets it on a shelf 2.00m high?

  1. How much work is done in lifting a 40.0kg bag of potatoes onto a table that is 1.50 metres high?
  1. An ice skater lifts his 60.0 kg partner a distance of 2.50 m into the air. Calculate the amount of energy required to do this.

7. Calculate the amount of work that would be required to drag the object a distance of 4.00 metres up the inclined plane?

8. a.) If there is a force of friction, which opposes the motion of 40.0 N, what total force would be needed before the object could be pulled up the inclined plane?

b.) How much work would be done in pulling the object a distance of 3.00 m up the incline?

  1. FIND: a.) Amount of force required to slide the mass up the inclined plane at constant velocity.

b) Amount of work done in sliding the mass up the 12.5m long incline.

c)Amount of work done if the 20.0kg object was lifted 5.00m directly off the ground, rather than using the inclined plane.

  1. Calculate the useful (horizontal) work done by a boy who pulls a sled a distance of 20.0m, using a 100N force directed 41.4º above the horizontal.
  1. A force of 80.0 N is applied to an angle of 53.1o above the horizontal. If the horizontal distance moved was 5.00m, find the amount of useful work done on the object.
  1. A 70.0 kg man ascends a flight of stairs. He climbs 15.0m (vertical height) in 20.0 seconds.

a.)How much work must be done?

b.)What power in watts does he develop?

  1. A certain motor can lift a 120 kg mass a distance of 3.00 metres in 4.00 seconds. What power in watts is the motor developing?
  1. A 60.0 kg man can run up a set of stairs whose vertical height is 3.50 metres, in 2.50 seconds. What power in watts is his body developing?
  1. A 400kg sled is pulled with a force of 100N directed 35o above the horizontal, and is moved 5.50 metres. Assuming no friction, calculate the amount of useful work done.

Answers

  1. 450 J
  2. 210 J
  3. 12000 J
  4. 147 J
  5. 588J
  6. 1470 J
  7. 352.3 J
  8. 353.5 Nb) 1060.5 J
  9. 78.5 Nb) 980.9 J c) 980 J
  10. 1500 J
  11. 240 J
  12. 10290 Jb) 514.5 W
  13. 882 W
  14. 823.2 W
  15. 450 J