Question

27. The motor connected to the pulley A is pulling a crate of mass 200 kg up the plane with constant
speed 5 m/s as shown fig. Find the tension in the string in KN, if the power delivered by motor is 10 KW.
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Answer 1

Given info : The motor connected to the pulley A is pulling a crate of mass 200 kg up the plane with constant

speed 5 m/s as shown fig.

To find : we have to find the tension in the string in kN if power delivered by motor is 10kW.

Solution : see figure,

component of weight along plane = mgsin37° = 200 × 10 × 3/5 = 1.2kN

let tension acting on the string is T.

then net force acting on the mass in upward direction is (T - mgsin37°) = (T - 1.2) kN

now power delivered by motor = speed of mass × net force acting on the mass

⇒ 10kN = 5 m/s × (T - 1.2) kN

⇒2 = T - 1.2

⇒T = 3.2 kN

therefore the tension in the string is 3.2kN