HARD
11th West Bengal Board
IMPORTANT
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A rockel weighs 15000 kg when it is on the launching pad on the surface of the earth. It is fired vertically upward and after all the fuel is burnt out, it weighs 5000 kg. The ejection of the fuel gas is at a constant rate of 5 kgs-1 with a constant velocity of 1700 ms-1 relative to the rocket.

Calculate the thrust of the rocket (Neglect gravity and air resistance.)

Important Questions on Newton's Laws of Motion

HARD
11th West Bengal Board
IMPORTANT

A rockel weighs 15000 kg when it is on the launching pad on the surface of the earth. It is fired vertically upward and after all the fuel is burnt out, it weighs 5000 kg. The ejection of the fuel gas is at a constant rate of 5 kgs-1 with a constant velocity of 1700 ms-1 relative to the rocket.

Calculate the final speed of the rocket after complete burn out of the fuel. (Neglect gravity and air resistance.)

HARD
11th West Bengal Board
IMPORTANT
A stream of water of density ρ flowing horizontally with a speed of gushes out of a tube of cross-sectional area A and hits a vertical wall nearby. Find the force of impact on the wall when the water does not rebound.
HARD
11th West Bengal Board
IMPORTANT

Two cubes of masses m1 and m2 lie on two frictionless slopes of block A which rests on a horizontal table. The cubes are connected by a string which passes over a pulley. (See Fig.) To what horizontal acceleration should the whole system (i.e., the block and cubes) be subjected so that the cubes do not slide down the plane? What is the tension in the sring in this situation?

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HARD
11th West Bengal Board
IMPORTANT
A load W is to be raised vertically from a point L to another point M by a chain which can withstand a maximum tension of kW where k is a constant. The height of M from L is x and the load is at rest at both the points. Show that the minimum time in which the ascent can be made is 2kx(k-1)g.
HARD
11th West Bengal Board
IMPORTANT

Two blocks of mass 2.9 kg and 1.9 kg are suspended from a rigid support S by two inextensible wires each of length 1 metre, see Fig. The upper wire has negligible mass and the lower wire has a uniform mass of 0.2 kg/m. The whole system of blocks, wires and support have an upward acceleration of 0.2 m/s2. Acceleration due to gravity is 9.8 m/s2.

Find the tension at the mid-point of lower wire,

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HARD
11th West Bengal Board
IMPORTANT

Two blocks of mass 2.9 kg and 1.9 kg are suspended from a rigid support S by two inextensible wires each of length 1 metre, see  . The upper wire has negligible mass and the lower wire has a uniform mass of 0.2 kg/m. The whole system of blocks, wires and support have an upward acceleration of 0.2 m/s2. Acceleration due to gravity is 9.8 m/s2.

Find the tension at the mid-point of upper wire

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HARD
11th West Bengal Board
IMPORTANT

A body of mass m moving with a velocity v in the X direction collides with another body of mass M moving in the Y -direction with a velocity V. They coalesce into one body during collision.

Calculate the direction and magnitude of the momentum of the final body,

HARD
11th West Bengal Board
IMPORTANT

A body of mass m moving with a velocity v in the X direction collides with another body of mass M moving in the Y -direction with a velocity V. They coalesce into one body during collision.

Calculate the fraction of initial kinetic energy transformed into heat during collision in terms of the two masses.