In a developing country a hand operated winch is used to raise bags of rice from
ID: 1958979 • Letter: I
Question
In a developing country a hand operated winch is used to raise bags of rice from the ground to the top of the processing mill.a) If 200kg of rice are raised 5m in 2 min what is the power input?
b) if the wind-up drum is 0.25 m in diameter what is the torque on the wind-up drum?
c) What force must one exert on the drum handles if they extend out 0.75m from the centre of the drum?
d) Could one person be expected to operate this winch?
e) If the drum of the winch was 1.5m diameter what would be the mass of rice one could lift when exerting the same force on the handles?
Explanation / Answer
a) power input = Energy required to lift it per unit time = 200 * 5 * g / 2 *60 ( where 'g' is acceleration due to gravity) = 25 * g / 3 Ans b) Torque on the wind up drum = (mg) * (0.25) N-m = 50*g N-m c) Force required would be enough to overcome the torque produced by gravity. It would be = 50*g/0.75 Newtons = 20*g/3 Newtons d) Yes e) Since radius of the winch is not changing (1.5/2 = 0.75 m), hence, the mass would remain same i.e., 200 kgs