Force and Laws of Motion (Practice Sheet ,Class 9)

(1)Which would exert a greater force to accelerate 5 kg mass at 2m/s2 acceleration or 2 kg mass at 5 m/s2 acceleration?

Solution-

(2)Ram whose mass is 80kg is going on his bike of 500 kg. He used brakes to stop the bike. He takes 2s to stop bike. Find the force exerted by the bike while velocity of the bike was 100km/h?

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(3)Two balls of mass 10kg and 20 kg are moving with a velocity of 5m/s and 8m/s in the same direction respectively. After collision they moved together. Find the combined velocity of them after collision.

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(4)A man wants to move a heavy stone at a distance of 5m. He is trying to do it hard but not able to move. His friend suggests him to get some more people to move it. In your opinion is he right?

Solution-

(5)An object of mass 100kg is accelerating from a velocity of 10m/s to 20m/s. Calculate change in momentum of the object.

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(6)An object is moving with velocity of 50m/s and covered 10km. Find the force applied on it if mass of the object is 200kg.

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(7)Two children are going on the road .Mass of the first child is 50kg and mass of the other child is 60kg and they are moving with the velocity of 10m/s and 8m/s respectively. Both are moving in opposite direction. If they collide what will be their combined velocity and also tell direction of their movement.

Solution-

(8)A tractor of mass 5000kg is pulling two carts of mass 2000kg each. Each cart is carrying 1000kg load. Tractor is moving with velocity of 50km/h I forward direction. He travels 10km in10s. Find net force of the tractor. Find the momentum of the tractor.

Solution-

(9)F =m a is

(i)Newton’s first law of motion

(ii) Newton’s second law of motion

(iii) Newton’s third law of motion

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(10)Law of conservation of the momentum is

(i)m1u1 + m2u2 = m1v1 + m2v2

(ii) mu =0

(iii)mv2 +mu2 =mvs

Solution-

Helping Topics

Force and Laws of Motion

NCERT solution class 9

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