Laws Of Motion CBSE Questions & Answers

Laws Of Motion

This is Physics Class 11 Laws of Motion CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
Impulse is a
  • A
    scalar and equals the change of mass
  • B
    vector and equals the change of momentum
    Correct
  • C
    vector and equals the change of mass
  • D
    vector and equals the inertia of momentum
2
Newton’s third law states that when two bodies interact,.
  • A
    they exert forces on each other that at each instant are equal in magnitude and opposite in direction
    Correct
  • B
    they exert forces on each other that at some instants are equal in magnitude and same in direction
  • C
    they exert forces on each other that at each instant are equal in magnitude and same in direction
  • D
    they exert forces on each other that at some instants are equal in magnitude and opposite in direction
3
Action and reaction forces are
  • A
    equal in magnitude and same in direction
  • B
    not equal in magnitude and opposite in direction
  • C
    not equal in magnitude and same in direction
  • D
    equal in magnitude and opposite in direction
    Correct
4
According to the law of conservation of momentum,
  • A
    the momentum of an interacting system of particles and fields is conserved
  • B
    the momentum of an isolated system of interacting particles is conserved
  • C
    the total momentum of an isolated system of interacting particles is conserved.
    Correct
  • D
    the total momentum of an interacting system of particles and fields is conserved
5
When bodies are in contact
  • A
    contact forces are equal and in same direction
  • B
    contact forces are not equal and opposite in direction
  • C
    contact forces are not equal and in same direction
  • D
    contact forces are equal and opposite in direction
    Correct
6
Friction is
  • A
    perpendicular to contact surface and aids motion
  • B
    parallel to contact surface and aids motion
  • C
    parallel to contact surface and opposes motion
    Correct
  • D
    perpendicular to contact surface and opposes i motion
7
Static friction force
  • A
    decreases before moving and increases later
  • B
    is a strong interaction force
  • C
    remains constant
  • D
    increases until the body starts to move
    Correct
8
Rolling friction is
  • A
    equal to static friction
  • B
    greater than or equal to static
  • C
    less than static friction
    Correct
  • D
    greater than static friction
9
The magnitude of the centripetal force is given by
  • A
    \(F = m{{{v^2}} \over {2R}}\)
  • B
    \(F = m{{{v^2}} \over R}\)
    Correct
  • C
    \(F = 2m{{{v^2}} \over R}\)
  • D
    \(F = m{{2{v^2}} \over R}\)
10
The centripetal force required for circular motion of a car such as taking a sharp turn is provided by
  • A
    contact force
  • B
    gravitational force
  • C
    static friction
    Correct
  • D
    rolling friction
11
In which of the following cases is the net force non zero?
  • A
    a drop of rain falling down with a constant speed
  • B
    a kite skillfully held stationary in the sky
  • C
    a cork of mass 10 g floating on water
  • D
    a coin falling under gravity
    Correct
12
In which of the following cases is the net force zero
  • A
    a feather falling under gravity
  • B
    a coin falling under gravity
  • C
    a rocket just before lift off
  • D
    a high-speed electron in space far from all material objects, and free of electric and magnetic fields
    Correct
13
A pebble of mass 0.05 kg is thrown vertically upwards. Give the direction and magnitude of the net force on the pebble, during its upward motion, Ignore air resistance
  • A
    0.05 N vertically down
  • B
    0
  • C
    0.5 N vertically down
    Correct
  • D
    0.5 N vertically up
14
A pebble of mass 0.05 kg is thrown vertically upwards. Give the direction and magnitude of the net force on the pebble, during its downward motion, Ignore air resistance
  • A
    0.5 N vertically up
  • B
    0.5 N vertically down
    Correct
  • C
    0.05 N vertically down
  • D
    0
15
A pebble of mass 0.05 kg is thrown vertically upwards. Give the direction and magnitude of the net force on the pebble, if the pebble was thrown at an angle of 45° with the horizontal direction, Ignore air resistance
  • A
    0
  • B
    0.5 N vertically down
    Correct
  • C
    0.5 N vertically up
  • D
    0.05 N vertically down