NCERT Class-9 Science Solutions: Chapter 9-Force And Laws Of Motion Part 1

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Multiple Choice Questions

Question 1:

Which of the following statement is not correct for an object moving along a straight path in an accelerated motion?

  1. Its speed keeps changing

  2. Its velocity always changes

  3. It always goes away from the earth

  4. A force is always acting on it

Answer: C

Image object on accelerated motion

Image Object on Accelerated Motion

Image object on accelerated motion

Question 2:

According to the third law of motion, action and reaction

  1. Always act on the same body

  2. Always act on different bodies in opposite directions

  3. Have same magnitude and directions

  4. Act on either body at normal to each other

Answer: B

Image the third low of motion

Image the Third Low of Motion

Image the third low of motion

Question 3:

A goalkeeper in a game of football pulls his hands backwards after holding the ball shot at the goal. This enables the goal keeper to

  1. Exert larger force on the ball

  2. Reduce the force exerted by the ball on hands

  3. Increase the rate of change of momentum

  4. Decrease the rate of change of momentum

Answer: B

Image football hands backwards

Image Football Hands Backwards

Image football hands backwards

Question 4:

The inertia of an object tends to cause the object

  1. To increase its speed

  2. To decrease its speed

  3. To resist any change in its state of motion

  4. To decelerate due to friction

Answer: C

Image in its state of motion

Image in Its State of Motion

Image in its state of motion

Question 5:

A passenger in a moving train tosses a coin which falls behind him. It means that motion of the train is

  1. Accelerated

  2. Uniform

  3. Retarded

  4. Along circular tracks

Answer: A

Image passenger in a moving train tosses a coin

Image Passenger in a Moving Train Tosses a Coin

Image passenger in a moving train tosses a coin

Question 6:

An object of mass is sliding with a constant velocity of on a frictionless horizontal table. The force required to keep the object moving with the same velocity is

Answer: B

Image same velocity is zero

Image Same Velocity is Zero

Image same velocity is zero

Question 7:

Rocket works on the principle of conservation of

  1. Mass

  2. Energy

  3. Momentum

  4. Velocity

Answer: C

Image Rocket works conservation of Momentum

Image Rocket Works Conservation of Momentum

Image Rocket works conservation of Momentum

Question 8:

A water tanker filled up to of its height is moving with a uniform speed.

On sudden application of the brake, the water in the tank would

  1. Move backward

  2. Move forward

  3. Be unaffected

  4. Rise upwards

Answer: B