- #1

emzee1

- 25

- 0

## Homework Statement

At the instant shown, point P on the cable has a velocity 12 m/s, which is

increasing at the rate of 6m/s^2. Determine the power input of motor M at this

instant if it operates with an efficiency of 0.8. The mass of the block A is 50kg. I've attached a picture of the problem.

## Homework Equations

F=ma

Power = F*v (F=force, v=velocity)

## The Attempt at a Solution

All I did was make an attempt at drawing free-body diagrams. For the block A of 50kg, I did:

2T-mg=ma; 2T-50(g)=50(6); T= 395 N

Then for point P, I assumed 395 = force of the motor, and thus:

395(12)= 4,740

Input Power = (4,740/.8) = 5,925 W

This is wrong obviously, and was hoping if someone could help me out on where I'm going wrong.