Question

Kinetic Energy RE-

Answer 1

Answer:

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

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