Question

A child is stationary on a swing.(a)The child is given a push by his brother to start him swinging.His brother applies a steady force of 84 N over a distance of 0.25 m.(i) Calculate the work done by this force.(2)..............................................................................................................................................(ii) State how much energy is transferred by this force.(1)..............................................................................................................................................(iii) After several more pushes, the child has a kinetic energy of 71 J.The mass of the child is 27 kg.Show that the velocity of the child at this point is about 2.3 m/s.(2)(iv) Which one of these quantities changes in both size and direction while he is swinging?Put a cross ( ) in the box next to your answer.(1)Ahis gravitational potential energyBhis momentumCthe force of gravity acting on himDhis kinetic energy

Answer 1

Answer:

Work done = Fs

Explanation:

(i) W = Fxs

= 84N x0.25m

= 21 Joules

(ii) Ek = 1/2mv^2

71 = 1/2×27×v^2

71×2/27 = v^2

v = 23m/s