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The horizontal force applied on the wedge is:Question Image

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Important Questions on Laws of Motion

MEDIUM
An object takes n times as much time to slide down a 45° rough inclined plane as it takes to slide down a perfectly smooth 45° inclined plane. The coefficient of kinetic friction between the rough plane and the object is
HARD

The machine as shown has 2 rods of length 1 m connected by a pivot at the top. The end of one rod is connected to the floor by a stationary pivot and the end of the other rod has roller that rolls along the floor in a slot. As the roller goes back and forth, a 2 kg weight moves up and down. If the roller is moving towards right at a constant speed, the weight moves up with a :

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MEDIUM

Calculate the acceleration of the block and trolly system shown in the figure. The coefficient of kinetic friction between the trolly and the surface is 0.05. (g=10 m s-2, mass of the string is negligible and no other friction exists).

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EASY
A block of mass 48 kg kept on a smooth horizontal surface is pulled by a rope of length 4 m by a horizontal force of 25 N applied to the other end. If the linear density of the rope is 0.5 kg m-1, the force acting on the block is
EASY
A body of weight W1 is suspended from the ceiling of a room through a chain of weight W2. The ceiling pulls the chain by a force
MEDIUM

Two blocks A and B of masses 1.5 kg and 0.5 kg respectively are connected by a massless inextensible string passing over a frictionless pulley as shown in the figure. Block A is lifted until block B touches the ground and then block A is released. The initial height of block A is 80 cm when block B just touches the ground. The maximum height reached by block B from the ground after the block A falls on the ground is

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EASY
Two bodies of mass 4 kg and 6 kg are tied to the ends of a massless string. The string passes over a pulley which is frictionless (see figure). The acceleration of the system in terms of acceleration due to gravity g is:
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MEDIUM
Two masses m1 and m2 are connected by a massless string over a fixed pulley. If m1>m2m1 will move downward and m2 will move upward. What is the acceleration with which the combination of two masses will move? (g= acceleration due to gravity)
EASY

Three forces of magnitude 6 N, 6 N and 72 N act at a cormer of a cube along three edges of a cube, as shown in the figure. The resultant of the three forces is

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EASY

Two equal forces are acting at a point, making an angle of 60° with each other. If their resultant force is equal to 403 N, the magnitude of each force is       

MEDIUM

An inclined plane making an angle of 30° with the horizontal is placed in a uniform horizontal electric field 200NC as shown in the figure. A body of mass 1 kg and charge 5 mC is allowed to slide down from rest at a height of 1 m. If the coefficient of friction is 0.2, find the time taken by the body to reach the bottom.
g=9.8 m s-2; sin30°=12; cos30°=32

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MEDIUM
A balloon with mass m is descending down with an acceleration a (where a<g). How much mass should be removed from it so that it starts moving up with an acceleration a?
MEDIUM

A boy of mass 4 kg is standing on a piece of wood having mass 5 kg. If the coefficient of friction between the wood and the floor is 0.5 , the maximum force that the boy can exert on the rope so that the piece of wood does not move from its place is _______ N. (Round off to the Nearest Integer)

[Take g=10 m s-2

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MEDIUM
Two blocks of masses m1 and m2 are suspended by a massless string passing over a smooth pulley. If the acceleration of the system is g8,then the ratio of the masses m2 m1=
MEDIUM

A steel block of 10 kg rests on a horizontal floor as shown. When three iron cylinders are placed on it as shown, the block and cylinders go down with an acceleration 0.2 m s-2. The normal reaction R' by the floor if mass of the iron cylinders are equal and of 20 kg each is in N,

[Take g=10 m s-2 and μs=0.2

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EASY

An object of mass m is being moved with a constant velocity under the action of an applied force of 2 N along a frictionless surface with following surface profile.

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The correct applied force vs distance graph will be :

MEDIUM

A block of mass m slides on the wooden wedge, which in turn slides backward on the horizontal surface. The acceleration of the block with respect to the wedge is:
Given m=8 kg, M=16 kg
Assume all the surfaces shown in the figure to be frictionless.

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MEDIUM
A force F1 of magnitude 4 N acts on an object of mass 1 kg at origin in a direction 30° above the positive x- axis. A second force F2 of magnitude 4 N acts on the same object in the direction of the positive y- axis. The magnitude of the acceleration of the object is nearly
MEDIUM

A rectangular frame of some mass has to be suspended symmetrically by two mass-less strings of equal length on two supports. It can be done in one of the three following ways as shown in below figures. The tension in the strings will be

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MEDIUM
Two blocks A and B of masses 3m and m respectively are connected by a massless and inextensible string. The whole system is suspended by a massless spring as shown in figure. The magnitudes of acceleration of A and B immediately after the string is cut, are respectively
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