Q17 of 48 Page 38

Which of the diagrams in Fig. 6.9 correctly shows the change in kinetic energy of an iron sphere falling freely in a lake having sufficient depth to impart it a terminal velocity?

When an iron sphere is falling freely in the lake, it will

accelerate first then its velocity increases and resistance


due to water causes a viscous force which oppose its


motion. Hence, during fall of the sphere, first its velocity


increases and then become constant after sometime.


option (b) is best representable graph of it.

More from this chapter

All 48 →
15

A raindrop falling from a height h above ground, attains a near terminal velocity when it has fallen through a height (3/4) h. Which of the diagrams shown in Fig. 6.8 correctly shows the change in kinetic and potential energy of the drop during its fall up to the ground?

 16

In a shotput event an athlete throws the shotput of mass 10 kg with an initial speed of 1m s-1 at 45° from a height 1.5 m above ground. Assuming air resistance to be negligible and acceleration due to gravity to be 10 m s -2, the kinetic energy of the shotput when it just reaches the ground will be

 18

A cricket ball of mass 150 g moving with a speed of 126 km/h hits at the middle of the bat, held firmly at its position by the batsman. The ball moves straight back to the bowler after hitting the bat. Assuming that collision between ball and bat is completely elastic and the two remain in contact for 0.001s, the force that the batsman had to apply to hold the bat firmly at its place would be

 19

A man, of mass m, standing at the bottom of the staircase, of height L climbs it and stands at its top.