Type C. On Work-energy theorem

14. A bullet of mass 20 g strikes a target with a velocity of 150 m/s and brought to rest after piercing 10 cm into it. Calculate the average force of resistance offered by target. 22,500 N

15.A bullet of mass 25 g was moving at the rate of 500 m/s After passing through a solid substance, it continued Ii move at the rate of 100 m/s. How much work had to do in passing through the substance? 3000 J

Two bodies of masses 2 g and 10 g have position vectors and respectively. Find the position vector and distance of CM. from the origin.

Sol. Here, g ; g,

and .The position vector of the centre of mass is given by

.

The distance of the centre of mass from the origin is given by

In the HCl molecule, the separation between the nuclei of the two atoms is about 1.27 A. Find the approximate location of the CM. of the molecule, given that chlorine atom is 35.5 times as massive as hydrogen atom and nearly all the mass of an atom is concentrated in its nucleolus.

[Ans. 1.235 A (from hydrogen atom)]