**511. A hoop and disc have same mass and radius. Their rotational K.E are related by an equation______________?**

A. K.E hoop = K.E disc

**B. K.E hoop = 2K.E disc**

C. K.E hoop = 1/2K.E disc

D. K.E hoop = 4K.E disc

**512. The critical speed of an artificial satellite is_______________?**

A. 8 Kms-1

B. 8.1 Kms-1

**C. 7.9 Kms-1**

D. 8 ms-1

**513. Geostationary satellite completes one rotation around the earth in_______________?**

A. 3 hours

B. 6 hours

C. 12 hours

**D. 24 hours**

**514. The radius of geostationary orbit from the centre of the earth is nearly______________?**

**A. 42000km**

B. 36000km

C. 24000 km

D. 18000 km

**515. According to Einstein, the gravitational interaction is possible between_______________?**

A. material objects only

**B. material objects and electromagnetic radiation only**

C. electromagnetic radiations

D. none of the above

**516. One radian is equal to______________?**

A. 67.3°

**B. 57.3°**

C. 87.3°

D. 60°

**517. The period of a circular motion is given by_______________?**

A. T = πv

B. T = πw.

C. T = 2πr

**D. T = 2πr/v**

**518. The direction of the linear velocity of a body moving in a circle is______________?**

A. along the axis of rotation

**B. along the tangent**

C. directed towards the centre

D. directed away from the centre

**519. hen a body moves in a circle, the angle between its linear velocity and angular velocity is always_______________?**

WA. 180°

B. 0°

**C. 90°**

D. 45°

**520. The circumference subtends an angle________________?**

A. π radian

**B. 2π radian**

C. π/2 radian

D. 4π radian