Spectacle lenses can be tested by dropping a small steel ball onto the lens, as shown in the figure below, and then checking the lens for damage.

The mass of the ball is 0.016kg, and the height is 1.27 m.

(a)In a test the ball bounced back to a height of 0.85 m.

(b) Calculate the speed of the ball just before impact.

(c)Calculate the speed of the ball just after impact.

(d)Calculate the change in momentum of the ball due to the impact.

(e)The time of contact was 40 ms. Calculate the average

force of the ball on the lens during the impact.

steel ball 1.27 m lens plinth