Question

1.A 50 N force is applied to a 20 kg cart which was displaced at 150 m from rest on a surface applying an opposing force of 30N.

1. Illustrate the free body diagram indicating all the forces acting on the cart.
2. How much work is done on the cart?
3. What is the final kinetic energy of the cart?
4. How fast is the cart moving?

2.Explain your reasoning in each item briefly and concisely.

1. Given the potential energy of a body, explain the relationship of the body’s mass and height.

Answer 1

1.

2. $W=F\cdot s\cdot\cos\alpha=(50-30)\cdot150\cdot1=3000\ (J)$

3. $\Delta KE=W=3000\ (J)$

4. $KE=\frac{mv^2}{2}\to v=\sqrt{2\cdot KE/m}=\sqrt{2\cdot 3000/20}=17.32\ (m/s)$

The potential energy of a body

$PE=mgh$ .