Question

practice: kinetic and potential energy
answer the following questions. make sure to show all work to receive credit. you may need a separate sheet of paper.

1. lauryn serves a volleyball with a mass of 2.1 kg. the ball leaves her hand with a speed of 30 m/s. find the energy of the ball.
2. a cinder block sits on a platform 20 m high. if it has a mass of 8 kg, find its energy.
3. a babys car seat sits on top of a bench 2 m tall. the baby and the car seat have a weight of 12 n. find the energy of the baby and its car seat.
4. a 1,120 kg car is travelling with a speed of 40 m/s. find its energy.
5. a bell hanging at the top of a tower has 8,550 j of energy. if it has a mass of 20 kg, find the height of the bell.
6. what is the mass of an object that has 324 j of energy and is moving at a speed of 9 m/s?

Explanation:

Step1: Identify the formula

The formula for gravitational potential energy is \(GPE = mgh\). But since weight \(W=mg\), the formula can also be written as \(GPE = Wh\).

Step2: Substitute the values

We are given \(W = 12\ N\) and \(h=2\ m\). Substitute these values into the formula \(GPE=Wh\).

$$GPE=(12)(2)$$

Step3: Calculate the result

$$GPE = 24\ J$$

Answer:

The energy (gravitational potential energy) of the baby and its car seat is \(24\ J\).