Question 5

A demolition ball is used by a crane to break the wall of a building.
The demolition ball, of mass 1 250 kg, is lifted by the crane to a point R at a height of
5,8 m above its lowest position in 60 s.
Ignore air friction.

5.1 Define the term power in words. (2)

5.2 Calculate the average power dissipated by the crane in lifting the demolition
ball to point R. (3)

The demolition ball is released from point R and strikes the wall at the lowest point of
its swing. The ball then moves 0,25 m HORIZONTALLY into the wall before coming to
5.3 Define the term conservative force. (2)

5.4 Is the force which the wall exerts on the ball a CONSERVATIVE or a

5.5 State the energy conversion that takes place during the downward swing of
the demolition ball. (1)

5.6 Using energy principles, calculate the magnitude of the average force exerted
on the ball while it moves into the wall. (5)

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