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Chapter 6: Problem 10

A truck is moving northward at \(55 \mathrm{mi} / \mathrm{h}\). Later, it's moving eastward at the same speed. Has its kinetic energy changed? Has work been done on the truck? Has a force acted on the truck? Explain.

Short Answer

Expert verified
The kinetic energy of the truck has not changed because its speed did not change. Work has been done because the truck moved in a new direction. A force must have acted on the truck to cause it to change its direction of motion.

Step by step solution

01

Establish kinetic energy equation

Kinetic energy is given by \(\frac{1}{2}mv^2\), where \(m\) is the mass and \(v\) is the velocity. Since the speed of the truck has not changed (staying at \(55 \mathrm{mi} / \mathrm{h}\)), and speed is the magnitude of velocity, the kinetic energy should therefore remain the same.
02

Discuss the concept of work

Work is done when a force acts upon an object to cause a displacement. In this case, the truck changed its direction but not its speed. Since the distance the truck moves is not zero, it means work has been done on it.
03

Discuss the role of force

Force is required to change an object’s velocity (this includes changing its direction of motion). In this case, for the truck to change direction, a force must have been applied.

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