Chapter 6, Problem 4RAT

A model airplane moves three times as fast as another identical model airplane. Compared to kinetic energy of the slower airplane, the kinetic energy of the faster airplane is

(a) the same for level flight.

(b) twice as much.

(c) four times as much.

(d) more than four times as much.

To determine

The correct option for the statement "A model airplane moves three times as fast as another identical model airplane. Compared to kinetic energy of the slower airplane, the kinetic energy of the faster airplane is".

Answer to Problem 4RAT

The correct option for the statement "A model airplane moves three times as fast as another identical model airplane. Compared to kinetic energy of the slower airplane, the kinetic energy of the faster airplane is" is option (d).

Explanation of Solution

The kinetic energy of an object depends on the mass and speed of the object. It is directly related to mass and square of object's speed. The mass of both airplanes are same because both are identical. The mass is same for both airplanes, so the mass does not change the kinetic energy of both airplanes.

The speed of the faster airplane is three times the speed of slower airplane, so the kinetic energy of the faster airplane becomes nine times the kinetic energy of the slower airplane. So, the kinetic energy of the faster airplane is more than four times the kinetic energy of the slower airplane.

Conclusion:

Therefore, the correct option for the statement "A model airplane moves three times as fast as another identical model airplane. Compared to kinetic energy of the slower airplane, the kinetic energy of the faster airplane is" is option (d).