A car with mass 1000 kg accelerates from rest to 20 m/s. What is its kinetic energy?

A car with mass 1000 kg accelerates from rest to 20 m/s. What is its kinetic energy?

• A. 100000 J
• B. 200000 J
• C. 400000 J
• D. 1000 J

Answer: (B)

Kinetic energy is 1/2 m v^2, so it depends on both mass and the square of speed—the speed term grows quickly, which is why speed has a big effect on energy. Plugging in the values: 1/2 × 1000 × (20)^2 = 500 × 400 = 200,000 joules. So the car’s kinetic energy is 200,000 J. This aligns with the given result because the energy of motion increases with both more mass and higher speed, and the speed is squared, making 20 m/s produce a large amount of energy.

Kinetic energy is 1/2 m v^2, so it depends on both mass and the square of speed—the speed term grows quickly, which is why speed has a big effect on energy.

Plugging in the values: 1/2 × 1000 × (20)^2 = 500 × 400 = 200,000 joules. So the car’s kinetic energy is 200,000 J. This aligns with the given result because the energy of motion increases with both more mass and higher speed, and the speed is squared, making 20 m/s produce a large amount of energy.