Question 21 : A particle of mass m is moving in a horizontal circle of radius R with uniform speed v. When it moves from one point to a diametrically opposite point its
1. momentum changes by 2 Mv2
2. kinetic energy changes by Mv2
3. kinetic energy changes by Mv²/4
4. momentum does not change
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Question 22 : A pulley one metre in diameter rotating at 600 r.p.m. is brought to rest in 80 sec. by a constant force of friction on its shaft. How many revolutions does it makes before coming to rest?
1. 200
2. 300
3. 400
4. 500
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Question 23 : A stone attached to a rope of length l = 80 cm is rotated with a speed of 240 r.p.m. At the moment when the velocity is directed vertically upwards, the rope breaks. To what height does the stone rise further?
1. 1.2 m
2. 20.6 m
3. 24.9 m
4. 41.2 m
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Question 24 : A satellite has mass m speed v and radius r, the force acting on it is:
1. mrv²
2. mv²/r²
3. zero
4. mv²/r
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Question 25 : A small body attached at the end of an inextensible string completes a vertical circle, then its
1. total mechanical energy remains constant
2. angular velocity remains constant
3. angular momentum remains constant
4. linear momentum remains constant
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Question 26 : A particle moving in a circle of radius 25 cm at 2 revolutions per second. The acceleration of the particle is S.I. unit is
1. 4π²
2. 3π²
3. 2π²
4. π²
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Question 27 : A particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of the particle. The motion takes place in a plane. It follows that
1. its velocity is constant
2. its acceleration is constant
3. its motion is circular
4. its motion is linear
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Question 28 : A particle revolves round a circular path. The acceleration of the particle is
1. along the tangent
2. along the radius
3. along the circumference of the circle
4. zero
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Question 29 : A particle is performing a U.C.M. Which is the wrong statement regarding its motion?
1. The velocity and acceleration vectors are perpendicular to each other
2. The acceleration vector is tangential to the circle
3. The acceleration vector is directed towards the centre of the circle
4. The velocity vector is tangential to the circle
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Question 30 : A motor cyclist moving with a velocity of 75 km/hr on a flat road takes a turn on the road at a point where the radius of curvature of the road is 20 m. If the g is 10 m/s² the maximum angle of banking with vertical for no skidding is
1. tan^-1 (6)
2. tan^-1 (2)
3. tan^-1 (4)
4. tan^-1 (12)
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