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]