Question

2 which object has the greatest kinetic energy?
a 2 kg ball at 2 m/s
a 3 kg ball at 3 m/s
a 4 kg ball at 1 m/s
a 1 kg ball at 4 m/s

Explanation:

Step1: Recall the formula for kinetic energy

The formula for kinetic energy is \( KE=\frac{1}{2}mv^{2} \), where \( m \) is the mass and \( v \) is the velocity.

Step2: Calculate kinetic energy for each option

• For option A: \( m = 1\space kg\), \(v = 4\space m/s\). Then \( KE_A=\frac{1}{2}\times1\times4^{2}=\frac{1}{2}\times1\times16 = 8\space J\)
• For option B: \( m = 4\space kg\), \(v = 1\space m/s\). Then \( KE_B=\frac{1}{2}\times4\times1^{2}=\frac{1}{2}\times4\times1= 2\space J\)
• For option C: \( m = 3\space kg\), \(v = 3\space m/s\). Then \( KE_C=\frac{1}{2}\times3\times3^{2}=\frac{1}{2}\times3\times9 = 13.5\space J\)
• For option D: \( m = 2\space kg\), \(v = 2\space m/s\). Then \( KE_D=\frac{1}{2}\times2\times2^{2}=\frac{1}{2}\times2\times4 = 4\space J\)

Answer:

C. A 3 kg ball at 3 m/s