Rotational Motion

Suppose universal gravitational constant starts to decrease then

Q: Suppose universal gravitational constant starts to decrease then

(a) Length of the year will increase

(b) Earth will follow a spiral path of decreasing radius

(c) Kinetic energy of earth will decrease

(d) All of the above

Ans: (a),(c)

A spaceship orbits the earth at a constant speed along a circular path. When an astronaut inside the spaceship releases an object, it does not move away from him. Which of the following is the most accurate reason for this ?

Q: A spaceship orbits the earth at a constant speed along a circular path. When an astronaut inside the spaceship releases an object, it does not move away from him. Which of the following is the most accurate reason for this ?

(a) The gravitational pull on the object sue to the earth is very weak at a large distance from the earth

(b) The gravitational forces on the object due to the spaceship exactly balance the gravitational pull on it due to the earth

(c) The astronaut and the object move along the same circular path due to earth’s gravitational pull

(d) An object moving in a circular path round the earth experiences on gravitational pull.

Ans: (c)

A rod of length l slides sown along the inclined wall as shown in Fig. At the instant when the speed of end A is v, the speed of B is

Q: A rod of length l slides sown along the inclined wall as shown in Fig. At the instant when the speed of end A is v , the speed of B is
Numerical

(a) $- \frac{v cos\alpha}{cos\beta}$

(b) $ \frac{v sin\alpha}{sin\beta}$

(c) $ \frac{v cos\beta}{cos\alpha}$

(d) $ – \frac{v cos\beta}{cos\alpha}$

Ans: (d)

Two particle A and B are situated at a distance d = 2 apart. Particle A has a velocity of u = 10 m/s at an angle of 60° and particle B has a velocity υ at an angle 30° as shown in Fig. The distance d between A and B is constant. The angular velocity of B with respect A is

Q: Two particle A and B are situated at a distance d = 2 apart. Particle A has a velocity of u = 10 m/s at an angle of 60° and particle B has a velocity υ at an angle 30° as shown in Fig. The distance d between A and B is constant. The angular velocity of B with respect A is

Numerical

(a) 5√3 rad/s

(b) 5/√3 rad/s

(c) 10√3 rad/s

(d) 10/√3 rad/s

Ans: (b)

A circular ring of wire of mass 0.5 kg and radius 2.5 m is rotation in its own plane about a perpendicular axis passing through its centre with a constant angular speed of 10 rps. The tension produced in the ring will be

Q: A circular ring of wire of mass 0.5 kg and radius 2.5 m is rotation in its own plane about a perpendicular axis passing through its centre with a constant angular speed of 10 rps. The tension produced in the ring will be

(a) 5 × 103 N

(b) 104 N

(c) 785 N

(d) None of these

Ans: (c)