Dynamics Example 3 © 2000 D.P. Maloney

It takes a snow plow 30 sec to push a 2640 kg pile of snow along a straight level road at 18 m/s. If the plow exerts a force of 7800 N on the snow, how much work does it do?

Physical Principles and/or Ideas: Definition of work, and distance traveled by an object

undergoing constant speed motion.

Solution: Work can be defined as the product of the force applied and the distance the object moves in the direction of the force. In this situation we know the force, but we do not know the distance. However, the plow pushes the snow along at a constant speed, which is given, for a known time. So, we can quickly calculate the distance traveled. It is:

And now we are in position to determine the work done, we get:

What is the kinetic energy of the snow pile? Does it change? Why or why not? What happens to the work done by the snow plow?