Question

what has more ke, an 8 - kg mass at 11 m/s or a 2 kg mass at 25 m/s?

Explanation:

Step1: Calculate kinetic energy for 8 - kg mass

The formula for kinetic energy is \(KE=\frac{1}{2}mv^{2}\). For \(m = 8\space kg\) and \(v=11\space m/s\), we have \(KE_1=\frac{1}{2}\times8\times11^{2}\).
First, calculate \(11^{2}=121\). Then \(\frac{1}{2}\times8\times121 = 4\times121=484\space J\).

Step2: Calculate kinetic energy for 2 - kg mass

For \(m = 2\space kg\) and \(v = 25\space m/s\), using the formula \(KE=\frac{1}{2}mv^{2}\), we get \(KE_2=\frac{1}{2}\times2\times25^{2}\).
First, calculate \(25^{2}=625\). Then \(\frac{1}{2}\times2\times625=625\space J\).

Answer:

The 2 - kg mass at 25 m/s has more kinetic energy.