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PHYSICSPRACTICE TEST

Q.1 A particle of mass 15 kg has an initial velocity  jˆ2iˆv1   !"!

 m/s. It collides with another body and

the impact time is 0.1 s, resulting in a velocity k ˆ5 jˆ4iˆ6v t   ##"!

 m/s after impact. The average

force of impact on the particle is :

(A) %Nk ˆ5 jˆ6iˆ1515   ## (B) Nk ˆ5 jˆ6iˆ515   !#

(C) $ %Nk ˆ5 jˆ6iˆ5150   #! (D) $ %Nk ˆ5 jˆ6iˆ5150   #!

Q.2 A ball is dropped h m above the floor if e is the coefficient of restitution, then after collision itrebounds to a height of 

(A) eh (B) e2h (C) e3h (D) (1 + e)h

Q.3 After a completely inelastic collision, two objects of the same mass and same initial speed are

found to move away together at half their initial speed. The angle between the initial velocities of 

the object is :

(A) 120° (B) 90° (C) 60° (D) none of these.

Q.4 Two skaters A and B of mass 50 kg and 70 kg respectively stand facing each other 6 cm apart.

They then pull on a rope stretched between them. How far has each moved when they meet

(A) both have moved 3 m (B) A moves 2.5m and B 2.5 m

(C) A moves 3.5 m and B 2.5 m (D) A moves 2 m and B 4 m

Q.5 A ball falls vertically onto a floor, with momentum P, and then bounces repeatedly. The coefficient

of restitution is e. The total momentum imparted by the ball to the floor is :

(A) p(1 + e) (B)e1

p

!(C) &

 '

 ()* 

+ #e

11p (D) &

 '

 ()* 

+ 

!

#

e1

e1p

Q.6 A particle of mass m moving with velocity u makes an elastic one- dimensional collision with a

stationary particle of mass m. They are in contact for a very brief time T. Their force of interactionincreases from zero to F0 linearly in time T/2, and decreases linearly to zero in further time T/2.

The magnitude of F0 is :

(A) mu/T (B) 2mu/T (C) mu/2T (D) none of these.

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PHYSICSPRACTICE TEST

Q.7 A particle strikes a horizontal frictionless floor with a speed u, at an angle , with the vertical, and

rebounds with a speed v, at an angle - with the vertical. The coefficient of restitution between the

particle and the floor is e. The magnitude of v is:

(A) eu (B) (1 - e)u

(C) ,#, 222 cosesinu (D) ,#, 222 cossineu

Q.8 A bullet of mass m hits a target of mass M hanging by a string and gets embedded in it.

If the block rises to a height h as a result of this collision, the velocity of the bullet before collision

is :

(A)   gh2v " (B)   ./0

123 #"

M

m1gh2v

(C) ./

012

3& '

 ()* 

+ #"m

M1gh2v (D)   .

/

012

3& '

 ()* 

+ !"M

m1gh2v

Q.9 Two particles of mass M and 2M are at a distance D apart. Under their mutual gravitational force

they start moving towards each other. The acceleration of their centre of mass when they are D/ 

2 apart is :

(A) 2D

GM2

(B) 2D

GM4

(C) 2D

GM8

(D) zero.

Q.10 A block of mass M is attached with a spring of 

spring constant K. The whole arrangement is

placed on a vehicle as shown in the figure.

If the vehicle starts moving towards right with

an acceleration a (there is no friction anywhere),

then

(A) maximum elongation in the spring is Ma/K

(B) Maximum elongation in the spring is 2Ma/K

(C) Maximum compression in the spring is 2Ma/K(D) None of these.

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PHYSICSPRACTICE TEST

Q.11 A body is fired from point P and strikes at Q inside a smooth circular wall as shown in the figure.

It rebounds to point S (diametrically opposite to P), then

(A) The coefficient of restitution is zero (B) The coefficient of restitution is 1

(C) Kinetic energy is not conserved (D) The coefficient of restitution is 1/ 3 .

Q.12 A particle of mass m moving with a speed v collides elastically with another particle of mass 2m

on a horizontal circular tube of radius R, then select the correct alternative(s).

(A) The time after which the next collision will take place isv

R24

(B) The time after which the next collision will take place is directly proportional to m

(C) The tie after which the next collision will take place is inversely proportional to m.

(D) None of these.

Q.13 A block of mass M is tied to one end of a massless rope. The other end of the rope is in the hands

of a man of mass 2M as shown in the figure. The block and the man are resting on a rough wedge

of mass M as shown in the figure. The whole system is resting on a smooth horizontal surface.

The man pulls the rope. Pulley is mass less and frictionless. What is the displacement of the

wedge when the block meets the pulley. (Man does not leave his position during the pull)

(A) 0.5 m (B) 1 m (C) zero (D) 2/3 m.

Q.14 If no external force acts on a system then which statement is wrong.

(A) Velocity of centre of mass remains constant

(B)Velocity of centre of mass is not constant

(C) Velocity of centre of mass may be zero

(D) Acceleration of centre of mass is zero.

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PHYSICSPRACTICE TEST

Q.15 If a ball collides elastically with a smooth horizontal floor, then

(A) 5 " 7 (B) u = v (C) 5 8 7 (D) u > v

 ANSWER KEY 

Q.1 B Q.2 B Q.3 A Q.4 C Q.5 D Q.6 B Q.7 C

Q.8 C Q.9 D Q.10 B Q.11 B Q.12 A Q.13 A Q.14 ACD

Q.15 AB