Answer to Question #154368 in Classical Mechanics for John smith

Question

1. A tow truck pulls a car from rest on a level road. The tow truck exerts a horizontal force of 1800 N on the car. The frictional force on the car is 950 N. Calculate the work done on the car by each of the following forces if the car is pulled forward 600 meters. a) the force of the tow truck on the car b) the force of friction c) the force of gravity d) the normal force

Answer 1

a) By the definition of the work done, we have:

$$W_{horizontal}=F_{horizontal}s=1800\ N\cdot 600\ m =1.08\cdot10^6\ J.$$

b) By the definition of the work done, we have:

$$W_{friction} = F_{friction}s=950\ N\cdot 600\ m=5.7\cdot10^5\ J.$$

c)-d) Since there is no motion in the vertical direction (the tow truck pulls a car in the horizontal direction), the work done on the car by the force of gravity and the normal force equals zero.

Answer:

a) $W_{horizontal}=1.08\cdot10^6\ J.$

b) $W_{friction} =5.7\cdot10^5\ J.$

c) $W_{gravity} = 0.$

d) $W_{normal} =0.$