Question

ron and judy each pull a 40 kg crate across a rough floor at constant speed for a distance of 2.0 m. ron pulls horizontally and judy pulls at an angle of 30 degrees above horizontal. the coefficient friction between each crate and the floor is 0.50.

a.) calculate the work done by ron

b.) calculate the work done by judy

c.) is the work ron does on his crate, more, less, or the same as the work judy does on her crate? does your answer make sense?

Answer 1

0-5 7 Fi fR net force n o Constant speed hence Rody case N FR - A ork dane by Racly = Fe x 0-5x40x16x2 = 400 J

Jocly Fi sin N mg N-Fisine t mg f f- 4N--Fsn 9- mg) Work dlene -in&mg fi mg 9-30 using COA O work done umg coA Msin &+ ces O 310.7 J 1-7 1 +

hence from the calculation shown the work done by Judy is less than the work done by ron. This is because the friction force acting on the mass is reduced by the judy,s vertical component of force hence the reduced work against friction.