(a) A stick partly immersed in water appears to be bent. Draw a ray diagram to show the bending of the stick when placed in water and viewed obliquely from above. On which phenomenon, it is based?

(b) Two parallel rays of orange and green light in air, meet an air-water interface as shown below

I. Complete the diagram for path inside water.

II. What conclusion will you draw for this?

(a) What are the necessary conditions for TIR?

(b) Draw a diagram to show how rays of light are totally reflected when fall normally on the face of a right angled prism. Where is this action of prism used?

Monu pulls a toy car through a distance of 20 m on smooth and horizontal floor. The string field in Monu's hand makes an angle 60° with horizontal surface. If the force applied by the Monu be 10N,

(a) calculate the work done by Monu is pulling the car.

(b) If the string makes an angle 30° with the horizontal surface, then calculate work done.

A coolie of mass 55 kg move a load of 25 kg on his head upto 50 stairs, each of height 20 cm in 50 s. If g is 10 m/s², then find

(a) gravitational force acting on coolie,

(b) work done by him

(c) his power in watt

(d) the gravitational force is increased by two times, then calculate the power.