Question

the mass and speed of 3 vehicles are shown:
a
800 kg, 10 m/s

1. rank the vehicles by momentum from greatest to least
2. rank the vehicles by kinetic energy from greatest to least

b
1000 kg, 20 m/s
c
90 kg, 80 m/s

Explanation:

Step1: Calculate momentum

Momentum formula: $p = mv$.
For vehicle A: $p_A=800\times10 = 8000\space kg\cdot m/s$.
For vehicle B: $p_B = 1000\times20=20000\space kg\cdot m/s$.
For vehicle C: $p_C=90\times80 = 7200\space kg\cdot m/s$.

Step2: Calculate kinetic energy

Kinetic energy formula: $K=\frac{1}{2}mv^{2}$.
For vehicle A: $K_A=\frac{1}{2}\times800\times10^{2}=40000\space J$.
For vehicle B: $K_B=\frac{1}{2}\times1000\times20^{2}=200000\space J$.
For vehicle C: $K_C=\frac{1}{2}\times90\times80^{2}=288000\space J$.

Answer:

1. B > A > C
2. C > B > A