A stone of 1 kg is thrown with a velocity of 20 ms–1 across the frozen surface of lake and comes to rest after travelling a distance of 50 m. What is the force of friction between the stone and the ice?

Question:

A stone of 1 kg is thrown with a velocity of 20 ms^–1 across the frozen surface of lake and comes to rest after travelling a distance of 50 m. What is the force of friction between the stone and the ice?

Answer:

According to question,

m = 1 kg, initial velocity u = 20 ms^–1

final velocity v = 0, distance s = 50 m

∴ from the formula

v²= u²+ 2as

0 = 20² + (2 x a x 50)

0 = 400 + 100a

-400/100 = a

a = -4 ms^–2

Frictional force F = ma

F = 1 X (-4)

F = -4N

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Chapter 8 NCERT Class 9 Science SOLUTIONS

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Chapter 8 NCERT Class 9 Science SOLUTIONS

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More NCERT Questions

An object of mass 100 kg is accelerated uniformly from a velocity of 5 ms–1 to 8 ms–1 in 6 s. Calculate the initial and final momentum of the object. Also find, the magnitude of the force exerted on the object.

An object of mass 100 kg is accelerated uniformly from a velocity of 5 ms–1 to 8 ms–1 in 6 s. Calculate the initial and final momentum of the object. Also find, the magnitude of the force exerted on the object.

A hockey ball of mass 200 g travelling at 10 ms–1. It struck by a hockey stick so as to return. It along it's original path with a velocity at 5 ms–1. Calculate the change of momentum occurred in the motion of the hockey ball by the force applied by the hockey stick.

Using a horizontal force of 200 N, we intend to move a wooden cabinet across a floor at a constant velocity. What is the friction force that will be exerted on the cabinet?

What is the momentum of an object of mass m, moving with a velocity v ?(a) (mv)2 (b) mv2 (c) 1/2 mv2 (d) mv

An automobile vehicle has a mass of 1500 kg. What must be the force between the vehicle and the road if the vehicle is to be stopped with a negative acceleration of 1.7 ms–2?

A 8000 kg engine pulls a train of 5 wagons each of 2000 kg along a horizontal track. If the engine exerts a force of 40000 N and the track after a friction force of 5000 N then calculate:(a) the net accelerating force.(b) the acceleration of the train, and(c) the force of wagon 1 on wagon 2

A truck starts from rest and rolls down a hill with a constant acceleration. It travells a distance of 400 m in 20s. Find it's acceleration. Find the force acting on it if it's mass is 7 tonnes (Hint) tonne = 1000 kg)

Why is it advised to tie any luggage kept on the roof of a bus with a rope?

When a carpet is beaten with a stick dust comes out of it. Explain.

1. An object experiences a net zero external unbalanced force. Is it possible for the object to be travelling with a non-zero velocity?

Why do you fall in the forward direction when a moving bus brakes to a stop and fall backwards when it accelerates from rest?

Explain why some of the leaves may get detached from a tree if we vigorously shake its branch.

Which of the following has more inertia: (A)a rubber ball and a stone of the same size? (B)a bicycle and a train? (C)a five rupees coin and a one-rupee coin?

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