Final answer:
The average power supplied to the block by friction while it slows from 13 m/s to 12 m/s is 6 W.
Step-by-step explanation:
To find the average power supplied to the block by friction, we first need to calculate the work done by friction. The work done by friction can be calculated using the equation work = force x distance. In this case, the force of friction is equal to the product of the coefficient of kinetic friction and the normal force. The distance is equal to the change in velocity (final velocity - initial velocity).
Using the equation work = force x distance, we can calculate the work done by friction. Then, we can calculate the time taken to slow down from 13 m/s to 12 m/s using the equation distance = velocity x time. Finally, the average power can be calculated using the equation power = work / time.
Plugging in the values, the average power supplied to the block by friction is approximately 6 W. Therefore, the correct answer is b) 6 W.