A car covers 72 kilometers in the first hour of its journey. In the next hour, it covers 90 kilometers. What is the amount of work done by the car? The total mass of the car, including its passengers, is 2.5 × 103 kilograms.
A.
2.8 × 105 joules
B.
4.0 × 105 joules
C.
5.1 × 105 joules
D.
2.8 × 106 joules
E.
2.8 × 107 joules

Question

A car covers 72 kilometers in the first hour of its journey. In the next hour, it covers 90 kilometers. What is the amount of work done by the car? The total mass of the car, including its passengers, is 2.5 × 103 kilograms.
A. 
2.8 × 105 joules
B. 
4.0 × 105 joules
C. 
5.1 × 105 joules
D. 
2.8 × 106 joules
E. 
2.8 × 107 joules

Vocaloid · Answer

Work done is equal to the change in kinetic energy

First convert both speeds to m/s (divide by 3600seconds/hr), then use KE = (1/2)mv^2 for both speeds. Subtract the two KE values to find the change in KE.