National Science Olympiad Model Paper 2 Questions and Answers Part 14

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Q. 5. A body is moving in a circular path with acceleration ‘a’ . If its velocity gets four times, find the ratio of acceleration after and before the change

A) 1: 16

B) 16: 1

C) 1: 4

D) 4: 1

Answer. B


When an object moves in circular path with constant speed then it acceleration is given as,

Condition first; Speed is 4 times increases then acceleration is given as,

Ratio of final to initial acceleration will be

= = 16: 1.

Q. 6. In the figure shown, the pulleys and strings are massless. The acceleration of the block of mass 4 m just after the system is released from rest is (θ = sin-13/5)

The Pulleys and Strings Are Massless

A) downwards

B) upwards

C) upwards

D) downwards

Answer: D


The Pulleys and Strings Are Massless

The Free body diagram of blocks is as shown From Newton՚s second law

… (i)

and … (ii)

= 4/5 and from constraint we get

… (iii)

Solving eq. (i) , (ii) and (iii) We get acceleration of block of mass 4m,


Q. 7. Two bodies of mass 5 kg and 8 kg are suspended at the ends of mass-less string passing over a frictionless pulley. The acceleration of the system is (g = 9.8m/s2)

A) 4.9m/s2

B) 2.26m/s2

C) 1.4m/s2

D) 9.5m/s2



Acceleration =

= = 2.26

Q. 8. A bullet of mass 10 g is shot from a gun of mass 5 kg. The muzzle velocity of the bullet is 800 m/s. The recoil velocity of the gun is

A) 1.6 m/s

B) 1600 m/s

C) 1 m/s

D) Data is insufficient

Answer: A


Momentum is a vector quantity, and therefore we need to use vector addition when summing together the momentum of the multiple bodies which make up a system.

Consider a system of two similar objects moving away from each other in opposite directions with equal speed and that the oppositely-directed vectors cancel out, so the momentum of the system as a whole is zero, even though both objects are moving.


By the conservation of linear momentum,

Let mass and velocity of bullet be and mass and velocity of gun is so

By the formula


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