Question

Kinetic Energy RE-

Mechanical Energy -KE+PE
Potential Energy
1. A baby carriage is sitting at the top of a hill that is 21 meters high. The carriage with the baby has a mass of 22kg.
Calculate the potential energy of this situation,
lergy at P.
the cart
2. A cinder block is sitting on a platform 20 meters high and it contains 250 Joules of potential energy. What is the mass
of this cinder block?
right tha
al with
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3. There is a 18kg bell at the top of a tower that a certain height from the ground. If the potential energy is calculated to be
760 Joules, determine the height of the tower.
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Kinetic Energy
4. What is the kinetic energy of a 55kg runner with a velocity of 14m/s?.
5. A car traveling on a road was found to have a Kinetic Energy of 69,759J. The car has a mass of 275Kg. How fast was
this car traveling?
6. Calculate the mass of a car that is travelling at a velocity of 38m/s and has a total energy of 12,700J.

Answer 1

1) The potential energy, P.E = 4527.6 J

2) The mass, m = 1.28 kg

3) The height of the bell, h = 4.31 m

4) The kinetic energy, K.E = 385 J

5) The velocity of the car, V = 22.53 m/s

6) The mass of the car, m = 17.59 kg

Step-by-step explanation:

1) The height of the hill, h = 21 m

The carriage with a baby has mass of, m = 22 kg

The potential energy,

P.E = mgh

= 22 x 9.8 x 21

= 4527.6 J

2) The height of the platform, h = 20 m

The P.E of the cinder block, P.E = 250 J

The mass,

m = P.E / gh

= 250 / (9.8 x 20)

= 1.28 kg

3) The mass of the bell, m = 18 kg

The P.E of the bell, P.E = 760 J

The height of the bell,

h = P.E/mg

= 760 / 18 x 9.8

= 4.31 m

4) The mass of the runner, m = 55 kg

The velocity of the runner, v = 14 m/s

The kinetic energy,

K.E = ½ mv²

= ½ x 55 x 14

= 385 J

5)The kinetic energy of the car, K.E = 69,759 J

The mass of the car, m = 275 kg

The velocity of the car,

V = √(2K.E/m)

V = √( 2 x 69759 / 275)

= 22.53 m/s

6) The velocity of the car, v = 38 m/s

The kinetic energy of the car, K.E = 12700 J

The mass of the car,

m = 2 K.E/ v²

= 2 x 12700 / 38²

m = 17.59 kg