Recitation Worksheet K Solutions

# Recitation Worksheet K Solutions - Worksheet K: Energy...

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Worksheet K: Energy Diagrams 1. A particle of mass m = 2 kg moves in a region of space with the following potential energy function. a. The force at x = 2 m is _ positive _____ (positive/negative/zero). In the interval x = [4,5] m, the force is __ negative ____ (positive/negative/zero). Explain. The force is minus the slope of the U(x) curve at each point. b. Estimate the magnitude of the force at x = 5 m. The slope of the U(x) curve at x = 5 m is the slope of the tangent line (in blue the figure). That line goes through points (4 m, -10 J) and (5 m, 20 J), so the force is: 20 ( 10) J 30 N 54 m U F x ∆− =− c. Find the work done by the force when the particle moves from x = 4 m to x = 5 m. () ( ) (5 m) (4 m) 20 ( 10) J 30 J WU U U =−∆ =− − − d. Is the sign of your answer to part c consistent with your answer to part a? Yes: if you move from 4 m to 5 m (displacement in the +x direction) and the force is in the –x direction, the work should be negative. e. Where is the force equal to zero?

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## This homework help was uploaded on 03/27/2008 for the course PHYS 221 taught by Professor Herrera-siklody during the Fall '08 term at Iowa State.

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Recitation Worksheet K Solutions - Worksheet K: Energy...

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