What is to be done to see shadow ?

What are shadows ?

A man, 2 m tall, walks at the rate of 1 (2)/(3) m/sec towards a street light which is 5 (1)/(3) m above the ground. At what rate is the tip of his shadow moving? At what rate is the length of the shadow changing when he is 3 (1)/(3) m from the light.

What is done to stop a moving ball?

What is thw work done by tension nin the string of a simple pendulum?