Answer: Calculate the work input in a pulley by using the previous readings in the correct mathematical equation. : Work (W) equals force (f) multiplied by distance (d), or W=fd. The work done by the pulley is the equation of weight (w) multiplied by height traveled (h).
Explanation:
Added potential energy = (mass) x (gravity) x (height)
or
Added potential energy = (weight) x (added height)
If you need to lift a 15N box 3m straight up, you have to increase its potential energy by (15 N) x (3 m) = 45 Joules .
Where is that added potential energy supposed to come from ? You could use an electric winch, a steam engine, a gasoline-powered motor, thousands of hamsters running on little treadmills that are are connected to the main pulley somehow, or your own arm muscles. But howEVER you do it, you have to provide <em>45 Joules</em> of WORK in order to increase the potential energy of the box by just that much.
To determine, the final velocity we use one kinematic equation. It would be 2ax = vf^2 - v0^2. The initial velocity would be zero since it starts from rest. Therefore, the equation would be:
vf = √(2ax) where a is the acceleration ( a = g ) and x is the height
vf = √(2)(9.8)(25)
vf = - 22.14 m/s
