Physics 163

Unit 5: Work, Energy and Power

Problem Set C

Problem 12:

A 47.1 gram Hot wheels car is moving along the ground with a speed of 3.62 m/s. It approaches a hill inclined at 23.1 degrees to the horizontal. It rolls up the hill and then back down. To what height (in meters) will the car roll up the incline? (Ignore any effects of rotation and friction.) Enter your answer accurate to the third decimal place.

• Read the problem carefully and diagram the physical situation (initial-final state diagram and/or work-energy bar chart)
• Identify known and unknown information in an organized manner (write on diagram)
• Take the time to plot out a strategy prior to beginning the solution (cancel terms in work-energy equation and perform conversions when necessary)
• Identify an appropriate formula to use
• Perform step-by-step algebraic manipulations

0.5 • m • vi2 + m • g • h i + F • d • cos = 0.5 • m • vf2 + m • g • h f

General information about work and energy problems is described on the Set C Overview page.

A detailed discussion of how to analyze physical situations using work-energy bar charts is provided online at The Physics Classroom.

A detailed description of the work-energy relationships for situation in which total mechanical energy is conserved is provided online at The Physics Classroom.