Laws of Motion

Question 501
CBSEENPH11020431

Out of the following pair, which one does NOT have identical dimensions is

  • angular momentum and Planck’s constant

  • impulse and momentum

  • moment of inertia and moment of a force

  • work and torque

Solution

C.

moment of inertia and moment of a force

Question 502
CBSEENPH11020437

A body A of mass M while falling vertically downwards under gravity breaks into two parts; a body B of mass 1/3 M and a body C of mass 2/3 M. The centre of mass of bodies B and C taken together shifts compared to that of body A towards

  • depends on height of breaking

  • does not shift

  • body C

  • body B

Solution

B.

does not shift

No horizontal external force is acting
∴ = acm =0
since vcm= 0
∴∆xcm = 0

Question 503
CBSEENPH11020438

A particle of mass 0.3 kg is subjected to a force F=−kx with k=15 N/m. What will be its initial acceleration if it is released from a point 20 cm away from the origin?

  • 3 m/s2

  • 15 m/s2

  • 5 m/s2

  • 10 m/s2

Solution

D.

10 m/s2

a = kx/m =10m /s2

Question 504
CBSEENPH11020439

The block of mass M moving on the frictionless horizontal surface collides with a spring of spring constant K and compresses it by length L. The maximum momentum of the block after collision is

  • square root of MK L
  • KL2/2M

  • zero

  • ML2/K

Solution

A.

square root of MK L 1 half KL squared space equals space fraction numerator straight P squared over denominator 2 straight m end fraction
therefore space straight P space equals space square root of MK straight L

NCERT Book Store

NCERT Sample Papers

Entrance Exams Preparation