Physics 163

Unit 5: Work, Energy and Power

Problem Set C

Problem 5:

A bowling ball is attached to a 2.3-meter long cable and hung from the ceiling. The cable is kept taut and the ball is raised to an initial height of 1.64 meters above the classroom floor. It is released from rest and allowed to swing as a pendulum. Determine its speed (in m/s) when it is at a height of .76 meters above the floor.

• 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.