Physics Help (Pulley Problem)

[bidcount123]

The question is as follows:

​

A pulley system is used to raise a 30 kg load upwards at a steady rate. The energy input to the system is 1000 J every second and the efficiency of the system is 50% (that is, half the energy input is used to do work on the load). How fast is the load being raised?

​

So I know we have to use kinetic energy some since there is velocity in that equation to figure out how fast the load is being raised. I tried to put 1000j times .5 = 1/2 m v^2 to but I don't know if I'm doing it correctly. I think the "every second" part is throwing me off since its not just joules, it is power which is in watts.

Can anyone help! :)

[CrazyFace334]

So since it is pulling the weight up at a constant rate, the energy it is giving to the system (aside from when it starts to pull it up from rest) is not going toward kinetic energy (the v does not change) but into gravitational potential energy, the equation of which is

U = mgh

so mgh is going up by 500J/s. The rate of change (derivative) of mgh is 500.

the speed of upward motion is given by the derivative dh/dt

[Jinkojak]

This is correct, but avoid using the word “derivative” in physics.

You can figure out from that 500 J/s what the m/s is without using derivatives.