Question

Two cars are driving down the road. Car A has a mass of 1,100 kg and is moving at 20 m/s. Car B is has a mass of 1,000 kg and is moving at 30 m/s. Which car has more kinetic energy and why?

A. car A because it has more mass and almost the same speed as car B
B. car B because it has a greater speed and almost the same mass as car A
C. car A because it has a lower speed and almost the same mass as car B
D. car B because it has less mass and almost the same speed as car A

Answer 1

Car B has more kinetic energy than Car A because kinetic energy is more sensitive to changes in speed than to changes in mass, and Car B is traveling at a higher speed.

Step-by-step explanation:

To determine which car has more kinetic energy, we use the formula for kinetic energy: EK = 1/2 mv2, where m is mass and v is velocity.

For Car A with mass 1,100 kg moving at 20 m/s,

its kinetic energy is calculated as EK = 1/2 × 1100 kg × (20 m/s)2 = 220,000 J.

For Car B with mass 1,000 kg moving at 30 m/s,

its kinetic energy is EK = 1/2 × 1000 kg × (30 m/s)2 = 450,000 J.

Comparing the kinetic energies, Car B has more kinetic energy due to its greater speed, despite having a slightly lower mass than Car A.

Thus, the correct answer is: B. car B because it has a greater speed and almost the same mass as car A.