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Two blocks A and B of equal mass m are connected through a massless string and arranged as shown in figure. The wedge is fixed on horizontal surface. Friction is absent everywhere. When the system is released from rest,

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Important Questions on Newton's Laws of Motion I

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JEE Main
IMPORTANT

In the figure shown, all the surfaces are smooth. All the blocks AB and C are movable, x-axis is horizontal and y-axis is vertical, as shown. Just after the system is released from the position as shown,

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JEE Main
IMPORTANT

An ideal spring, with a pointer attached to its end, hangs next to a scale. With 100 N weight attached and in equilibrium, the pointer indicates 40 on the scale, as shown. Using a 200 N weight instead results in 60 on the scale. Using an unknown weight X instead results in 30 on the scale. Find the value of X.

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JEE Main
IMPORTANT
In an elevator, a system is arranged as shown in the figure. Initially, the elevator is at rest and the system is in equilibrium with the middle spring unstretched. When the elevator accelerates upwards, it was found that for the new equilibrium position (with respect to the lift), the further extension in the top spring is 1.5 times that of the further compression in the bottom spring, irrespective of the value of acceleration.

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(a) Find the value of m1m2 in terms of spring constants for this to happen.

(b) If k1=k2=k3=500 N m-1 and m1=2 kg and acceleration of the elevator is 2.5 m s-2find the tension in the middle spring in the final equilibrium with respect to the lift.

MEDIUM
JEE Main
IMPORTANT

A spring balance and a physical balance are kept in a lift. In these balances, equal masses are placed. Now, if the lift starts moving upwards with constant acceleration, then,

MEDIUM
JEE Main
IMPORTANT

The masses of 10 kg and 20 kg, respectively, are connected by a massless spring, as shown in the figure. A force of 200 N acts on the 20 kg mass. At the instant shown, the 10 kg mass has acceleration 12 m s-2. What is the acceleration of 20 kg mass?

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MEDIUM
JEE Main
IMPORTANT

An ideal spring is compressed and placed horizontally between a vertical fixed wall and a block, free to slide over a smooth horizontal tabletop as shown in the figure. The system is released from rest. The graph which represents the relation between the magnitude of the acceleration a of the block and the distance x travelled by it (as long as the spring is compressed) is,

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JEE Main
IMPORTANT

Two blocks of masses m1 and m2, which are connected with a light string, are placed over a frictionless pulley. This set-up is placed over a weighing machine, as shown. Three combinations of masses m1 and m2 are used. In the first case, m1= 6 kg and m2=2 kg, in second case, m1=5 kg and m2=3 kg and in the third case, m1=4 kg and m2=4 kg. The masses are held stationary initially and then released. If the readings of the weighing machine after the release, in three cases, are W1, W2 and W3, respectively, then,

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