When the handle on a car jack moves 60 cm, the 10,000 N carmoves upward 1.2 cm.

Question

When the handle on a car jack moves 60 cm, the 10,000 N carmoves upward 1.2 cm. There is no friction. Find (a) the work doneon the car, (b) the force exerted on the jack handle, (c) themechanical advantage. I got this question wrong on my homework. I have no idea howto do it. Can someone please help me. When the handle on a car jack moves 60 cm, the 10,000 N carmoves upward 1.2 cm. There is no friction. Find (a) the work doneon the car, (b) the force exerted on the jack handle, (c) themechanical advantage. I got this question wrong on my homework. I have no idea howto do it. Can someone please help me.

Explanation / Answer

Work is force times distance moved in thedirection of the force, so the work done on the car is 10,000 N *0.012 m = 120 J. (1 Joule is 1 Nm.)

Since there is no loss due to friction, that same amount of workmust have been done on the jack handle. If work is force timesdistance then work divided by distance is force, so the force onthe jack handle was 120 J / 0.6 m = 200 N.

The mechanical advantage is the ratio of the input distance to theoutput distance. That's 0.6 / 0.012 which is 50. (The units don'tmatter as long as they're the same in the numerator as they are inthe denominator so that they cancel out. 60 / 1.2 would give thesame answer.)

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