Question

A man does 50.0 J of work to push a 3.0kg shopping cart out of her way. If the cart started from rest, what was its speed immediately after this push? (Assume there is no friction.)

Answer 1

Answer 2

1. First, recall the formula of the work - energy theorem:

• \(W=\Delta E_{k}\). For an object starting from rest (\(v_{0} = 0\)), \(W=\frac{1}{2}mv^{2}\), where W is the work done by the external force, m is the mass of the object, and v is the final velocity.

2. Then, transform the formula to solve for v:

• From \(W = \frac{1}{2}mv^{2}\), we can get \(v=\sqrt{\frac{2W}{m}}\).

3. Finally, substitute the given values into the formula:

• Given that \(W = 50.0J\) and \(m = 3.0kg\), then \(v=\sqrt{\frac{2\times50.0}{3.0}}=\sqrt{\frac{100}{3}}\approx5.8m/s\).