Physics Assignment ‐ ENERGY PROBLEMS
[
/35]
Word Problems
Answer all word problems on a separate sheet of paper.
Breakdown of points:
1 point for showing knowns/unknowns (and showing correct conversions if necessary)
1 point for showing proper equation/formula
1 point for using the equation/formula correctly (process)
1 point for calculating correct answer and showing correct unit
(Example: A word problem that requires the use of only one step, or one equation/formula, will be graded as shown above, and will
be graded out of four possible points. A two‐step problem will be graded out of seven possible points ‐ SO SHOW ALL YOUR STEPS!)
[use equations/formulae from your notes ‐ remember that g = 9.8 m/s2]
1. A 65 kg student climbs a 40.0 m flight of stairs in 15.0 s. Calculate the gravitational potential
energy at the top of the stairs. (HINT: 1 step problem ‐ use only one equation!) [4 points]
2. A go‐cart derby is about to start and Marisa pushes her 15.0 kg cart to the start line 10.0 m up the
hill. Calculate the work done by Marisa on the go‐cart over the 10.0 m if friction is ignored. (HINT:
1 or 2 step problem ‐ use one or two equations to get to the answer!) [7 points]
3. A large electromagnet is lifting a 2000 kg minivan by doing 30000 J of work. How high is the
minivan being lifted? (HINT: 1 or 2 step problem ‐ use one or two equations to get to the
answer!) [7 points]
4. A 200.0 N force moves a 120.0 kg crate on a frictionless surface at a speed of 9.6 m/s. What is the
displacement of the crate? (HINT: 2 step problem ‐ use two equations!) [7 points]
Short Answers
Answer all questions on a separate piece of paper.
Please use complete sentences for full points.
5. (a) Describe three different situations/examples in which gravity does positive work, negative
work, and zero work. [3 points]
(b) Explain the conditions in the above situations that determine if positive, negative, or zero
work is done. (HINT: Discuss the direction of the force applied compared to the direction of
the distance for each situation) [3 points]
6. Explain four situations that would result in a world without gravitational potential energy.
[4 points]