Question

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?

Answer 1

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