A 60N block is pushed up a 2m long ramp. What is the efficiency of the ramp if 30N of force is needed to raise the block 0.5m?
Efficiency is defined as the ratio of useful output work to the input work. In this case, the useful output work is the work done on the block to raise it up the ramp, and the input work is the work done by the person pushing the block.
The useful output work is given by the force applied to the block multiplied by the distance it is raised:
Useful output work = force * distance = 30 N * 0.5 m = 15 Nm
The input work is given by the force applied by the person pushing the block multiplied by the distance the block is moved:
Input work = force * distance = 60 N * 2 m = 120 Nm
Therefore, the efficiency of the ramp is:
Efficiency = Useful output work / Input work = 15 Nm / 120 Nm = 0.125 or 12.5%