A body comes and sits suddenly on a circular rotating table the quantity which conserved is
A. angular velocity
B. angular momentum
C. linear momentum
D. angular acceleration
1 Answers
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If angular momentum is conserved in a system whose moment of inertia is decreased, will rotational kinetic energy be conserved.
Correct Answer - A Torque, `tau =(dL)/(dt)` where, L = angular momentum If `tau =0`, then `(d L)/(dt)=0` i.e. L = constant
2 Answers 5 views
A coin placed on a rotating table just slip when it is placed at a distance 4 r from the centre, on doubling the angular velocity of the table , the c
Correct Answer - C `r_(2) onega_(1)^(2)` `r_(2)=(r_(1) omega_(1)^(2))/(omega_(2)^(2))=(4r_(1) omega_(1)^(2))/(4 omega_(1)^(2)` `r_(2)=r`
2 Answers 1 views
A coin is place at a distance 9 cm from centre on a rotating turn table slip. If the angular velocity of the turn table is tripled, then the distance
Correct Answer - D `r_(2) omega_(2)^(2)=r_(1) omega _(1)^(2)` `r2=r_(1)omega_(1)^(2)/(omega_(2)^(2))=(9xxomega_(1)^(2))/(9 omega_(1)^(2))=1 cm` `r2=1cm`.
2 Answers 1 views
A body of moment of inertia about its axis of rotation is `3 kg m^(2)` and angular velocity 3 rad/s. The kinetic energy of rotating body is same as th
Correct Answer - A `(1)/(2)mv^(2)=(1)/(2)I omega^(2)`
2 Answers 1 views
A wheel is rotating with frequency of 500 rpm on a shaft, second identical wheel initially at rest is suddenly coupled on same shaft. The frequency of
Correct Answer - C `I_(1)omega_(1)=I_(2)omega_(2)` `I_(1)omega_(1)=2I_(1)omega_(2)` `therefore omega_(2)=(500)/(2)=250` rpm
2 Answers 4 views
A ring of mass m and radius R is rolling on a horizontal plane. If the ring suddenly starts rotating about its diameter, then its angular velocity in
Correct Answer - B `KE_("roll")=KE_("rot")` `(1)/(2)mv^(2)(1+(k^(2))/(R^(2)))=(1)/(2)m omega^(2)` `mv^(2)(1+(k^(2))/(R_(2)))=(mR^(2))/(4)omega^(2)` `omega =(2v)/(R )`
2 Answers 1 views
A body of mass 2 kg and radius of gyration 0.5 m is rotating about an axis. If its angular speed is 2 rad/s, then the angular momentum of the body wil
Correct Answer - A `L = I omega = mK^(2)omega`
2 Answers 4 views
If a satellite is moved from one stable circular orbit to a farther stable circular orbit, then the following quantity increases
Correct Answer - D Orbital speed `v_(c )=sqrt((GM)/(r ))`, Gravitational force `prop (1)/(r^(2))`, c.p. acceleration `=(v^(2))/(r )` All the three decrease as the orbital radius is increased. But the gravitational P.E....
2 Answers 1 views
Assertion : In photon-particle collision the total energy and total momentum are conserved. Reason : The number of photons are conserved in a collisio
Correct Answer - C (c ) : In a photon-particle collision such as photon-electron collision, the total energy and total momentum are conserved. However of photons may not be conserved in...
2 Answers 2 views
The wheel of a car is rotating at the rate of 1200 revolutions per minute. On pressing the accelerator for 10 seconds, it starts rotating at 4500 revo
Correct Answer - D Angular acceleration, `alpha=(2pi(n_2-n_1))/t=(2pi(3300/60))/10` `=11pi=(11pixx180)/pi=1980 degs^(-2)`
2 Answers 1 views