Question

Use 9.81 m/s² for acceleration due to gravity.

An electric winch lifts a 20 kg crate 2.5 meters. If the winch must not exceed 100 watts during use, what is the fastest time that could be used to lift the crate?

5 seconds
3 seconds
6 seconds
4 seconds

Answer 1

We can use the formula:

Power = Work / Time

Power is given as 100 watts, the work done is equal to the force required to lift the crate multiplied by the distance lifted. The force required is equal to the weight of the crate, which is:

Force = mass x acceleration due to gravity
Force = 20 kg x 9.81 m/s^2 = 196.2 N

So, the work done is:

Work = Force x Distance
Work = 196.2 N x 2.5 m = 490.5 J

Now, we can solve for time:

Time = Work / Power
Time = 490.5 J / 100 watts = 4.905 seconds

Therefore, the fastest time that could be used to lift the crate without exceeding 100 watts of power is approximately 4.9 seconds.

It'd be 5 Seconds!