Question

A 100 kg woman rode her 200 kg motorcycle in the race. She started from rest and at the end of the race she was moving at 15 m/s. What is the change in kinetic energy for both the woman AND her motorcycle? Pls show your work!!

Answer 1

The change in kinetic energy was 34 kJ.

Step 1. Calculate the total mass

Total mass = 100 kg + 200 kg = 300 kg

Step 2. Calculate the initial kinetic energy (KE_i)

v = 0

KE_i = ½ mv^2 = ½ × 300 kg × 0^2 = 0

Step 3. Calculate the final kinetic energy (KE_f)

KE_f = ½ mv^2 = ½ × 300 kg × [15 m·s^(-1)]^2 = 34 000 kg·m^2s^(-2) = 34 000 J = 34 kJ

Step 4. Calculate the change in kinetic energy

ΔKE = KE_f - KE_i = 34 kJ – 0 = 34 kJ