2019-03-01_Physics_Times

spring is then compressed a distance of x and

released. When the ball reaches the maximum

height of its trajectory, it is travelling at a speed v.

Then a different ball, weighing four as much as the

first, is placed on the spring which is still at an

angle .The spring is again compressed at a

distance x and released. Compared to the first ball,

the second ball reaches a maximum height that is

(a) 4 times higher (b) sin^2  times as high

(c)

v g^2

x

times as high (d) 1/4 times as high

A child is sitting at one end of a long trolley moving

with a uniform speed v on a smooth horizontal track.

If the child starts running towards the other end of

the trolley with a speed u (w.r.t trolley), the speed

of the centre of mass of the system is

(a) v - u (b) u + v

(c) v (d) None of these

A ball of mass m elastically collides with a wall with

velocity v, then change in its momentum is equal to

(a) 8 mv (b) 2 mv (c) zero (d) 2 m

A particle of mass m collides with another stationary

particle of mass M. If the particle m stops just after

collision, the coefficient of restitution for collision

is equal to

(a)

m

M

(b) 1

(c)

m

M m

(d)

M m

M m





The figure shows a man of mass m standing at the

end A of a trolley of mass M placed at rest on a

smooth horizontal surface. The man starts moving

towards the end B with a velocity urelwith respect

to the trolley. The length of the trolley is L.

When the man starts moving, then the velocity of

the trolley with respect to ground will be:

(a) rel

mu

m M

(b) rel

M

u

m

(c)

Murel

m M

(d) rel

m

u

M

If a ball collides with a wall at an angle of 45  and

rebounds perpendicularly with its initial direction

then find the impulse acting on the ball

Centre of Mass, Linear Momentum & Collision
11.

15.

(a) 2 cos45mv iˆ (b) mvcos45iˆ

(c) 2 cos45mv iˆ (d) mvcos45iˆ

d b c a b

b a b d d

d b a a a