A boy has to lift a load of mass 50 kg to a height of 1 m. (a) what effort is required if he lifts it directly? Take g = 10 N kg-1 (b) If the boy can exert a maximum effort of 250 N, so he uses an inclined plane to lift the load up. What should be the minimum length of the plank used by him?

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1 Answers

Mass of load m = 50 kg

Force required to lift a load 1 meter (h) = mxg = 50x10 = 500N

The maximum effort exerted by boy E =250 N

Load L = 500N

Mechanical advantage M.A = load/effort = 500/250 = 2

M.A = I/h

Height (h) =1m

Minimum length of plank l = MA x h = 2x1 = 2m

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