A 1500 kg (weight of 14,700 N) steel beam is lowered straight downward at a cons

Question

A 1500 kg (weight of 14,700 N) steel beam is lowered straight downward at a constant acceleration by a cable from a crane. The beam goes from rest when 30 m above the ground to dropping at 2.5 m/s when at a height of 10m above the ground.

Draw a free body diagram of the beam with two forces: the Tension straight up and the force of gravity (the weight) straight down.

From the motion, what is the acceleration of the beam?

What is the tension (magnitude) in the cable as the beam accelerates downwards?

Explanation / Answer

The equation is as follows -
M*g - T = M*a

Calculating Acceleration, =
Initial Speed = 0
Final Speed = 2.5m/s
Distance travelled = 20 m

V^2 = u^2 + 2*a*s
2.5^2 = 0 + 2*a*20
a = 0.156 m/s^2

Acceleration of the beam , a = 0.156 m/s^2

Calculating Tension,
M*g - T = M*a
14700 - T = 1500*0.156
T = 14,466 N
Tension in the Cable , T = 14,466 N

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