A car moves at a speed of 20ms-1 on a banked track and describes an arc of a circle of radius . The angle of banking is (take g = 10 ms-2)
25°
60°
45°
30°
When a body is projected vertically up from the ground with certain velocity, its potential energy and kinetic energy at a point A are in the ratio 2 : 3. If the same body is projected with double the previous velocity, then at the same point A the ratio of its potential energy to kinetic energy is
9 : 1
2 : 9
1 : 9
9 : 2
A spring with force constant k is initially stretched by x1. If it is further stretched by x2, then the increase in its potential energy is
A force Fx acts on a particle such that its position x changes as shown in the figure.
The work done by the particle as it moves from x = 0 to 20 m is
37.5 J
10 J
45 J
22.5 J
Two objects P and Q initially at rest move towards each other under mutual force of attraction. At the instant when the velocity of P is v and that of Q is 2v, the velocity of centre of mass of the system is
v
3v
zero
1.5 v
A body rolls down an inclined plane . If its kinetic energy of rotation is 40% of its kinetic energy of translation motion, then the body is
hollow cylinder
ring
solid disc
solid sphere
A circular disc A and a ring B have same mass and same radius. If they are rotated with the same angular speed about their own axis, then
A has less moment of inertia than B
A has less rotational kinetic energy than B
A and B have the same angular momentum
A has greater angular momentum than B
Angular momentum of the Earth revolving around the Sun in a circular orbit of radius R is proportional to
R
R2
R1/3
A.
We know that angular momentum of the earth
L = mvR
⇒ L =
⇒ L ∝ R1/2
⇒ L =
A body of mass m is released from a height equal to the radius R of the Earth. The velocity with which it will strike the Earth's surface is
A satellite revolves around the Earth of radius R in a circular orbit of radius 3R. The percentage increase in energy required to lift it to an orbit of radius 5R is
10 %
20 %
30 %
40 %