Paul lifts a sack weighing 245 newtons vertically from the ground and places it on a platform at a height of 0.7 meters. If he takes 10 seconds to do this task, what power has he expended during this time?
To calculate the power expended by Paul during the task, we can use the formula:
Power = Work / Time
The work done in lifting the sack vertically can be calculated as the product of the force applied (245 newtons) and the distance moved (0.7 meters):
Work = Force * Distance
Work = 245 N * 0.7 m = 171.5 joules
Now, we can substitute the value of work and the given time into the power formula:
Power = 171.5 J / 10 s
Power = 17.15 watts
Therefore, Paul has expended an average power of 17.15 watts during the 10 seconds it took to lift the sack vertically.
power=work/time=force*distance/time
= 245*.7/10 watts