Question

mr. starr pushed a cart full of groceries to this car. after emptying the cart, he pushed it back to the store. he pushed the cart at a speed of 2 meters per second each way. which is the best prediction? (1 point)
when it was full, the cart had less kinetic energy.
the carts kinetic energy depends on mr. starrs mass.
when it was empty, the cart had less kinetic energy.
the cart had the same kinetic energy going each way.

Explanation:

Step1: Recall the formula for kinetic energy

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

Step2: Analyze the speed and mass in each case

The speed \(v = 2\space m/s\) is the same for both the full - cart and the empty - cart cases. But the mass \(m\) of the full cart (\(m_{full}\)) is greater than the mass of the empty cart (\(m_{empty}\)), i.e., \(m_{full}>m_{empty}\).

Step3: Compare the kinetic energies

Using the formula \(K=\frac{1}{2}mv^{2}\), for the full cart \(K_{full}=\frac{1}{2}m_{full}v^{2}\) and for the empty cart \(K_{empty}=\frac{1}{2}m_{empty}v^{2}\). Since \(v\) is the same (\(v = 2\space m/s\)) and \(m_{full}>m_{empty}\), we have \(K_{full}>K_{empty}\)

Answer:

When it was empty, the cart had less kinetic energy.