SYSTEM OF PARTICLES AND ROTATIONAL DYNAMICS NEET/JEE LEVEL

A particle is confined to rotate in a circular path with decreasing linear speed. Then which of the following is correct?

• angular momentum is conserved about the centre

• only the direction of L is conserved

• it spirals towards the centre

• its acceleration is towards the centre

A SYSTEM CONSISTS OF MASS M AND m(<M).THE CENTRE OF MASS OF THE SYSTEM IS:

• AT THE MIDDLE

• NEARER TO M

• NEARER TO m

• AT THE POSITION OF LARGE MASS

TWO SKATERS A AND B WEIGHING 40kg AND 60kg RESPECTIVELY STAND FACING EACH OTHER 5m APART. IF THEY PULL A LIGHT ROPE STRECHED BETWEEN THEM , THEN THEY MEET AT

• 1.5 m APART FROM A

• 2m APART FROM A

• 2.5m FROM A

• 3.0 m FROM A

THE ANGULAR DISPLACEMENT OF A PARTICLE IS GIVEN BY θ=t^3+t^2+t+1 WHERE(t)IS TIME IN SECONDS.ITS ANGULAR ACCELERATION AT t=2sec is

• 14 rads^-2

• 17 rads^-2

• 12 rads ^-2

• 9 rads^-2

A WHEEL OF MASS 6kg IS ROTATING AT 3000rpm . ITS ANGULAR VELOCITY WILL BE

• 31.4 rad/sec

• 3.14 rad/sec

• 0.314 rad/sec

• 0.03 rad/sec

THE DIAMETER OF FLYWE

WHEEL IS INCREASED BY 1%.THE PERCENTAGE INCREASE IN MOMENT OF INERTIA ABOUT AXIS OF SYMMETRY WILL BE

• 1%

• 2%

• 3%

• 4%

THE ROTATIONAL ANALOGUE OF FORCEIN LINEAR MOTION IS

• TORQUE

• WEIGHT

• MOMENT OF INERTIA

• ANGULAR MOMENTUM

A BODY OF MASS 1kg IS ROTATING ON A CIRCULAR PATH OF DIAMETER 2m AT THE RATE OF 10 ROTATIONS IN 31.4sec .THE ANGULAR MOMENTUM OF THE BODY IS (IN kg.m^2/s)

• 3

• 4

• 2

• 1

A DISC OF RADIUS 2m AND MASS 100kg ROLLS ON A HORIZONTAL FLOOR. ITS CENTRE OF MASS HAS SPEED OF 20cm/s HOW MUCH WORK IS NEEDED TO STOP IT

• 3J

• 30kJ

• 2J

• 1J

THE ANGULAR SPEED OF THE WHEEL OF A VEHICLE IS INCREASED FROM 360rpm TO 1200rpm IN 14 SECOND.ITS ANGULAR ACCELERATION IS

• 2π rad/ s2

• 28 π rad/s2

• 120π rad /s2

• 1π rad/s2