Ch 5 Remaining New.docx

1.

Choose the wrong statement. The orbital velocity of a body in a stable orbit around a planet depends upon

2.

3.

a. the varage radius of the planet

b. the height of the body above the planet

c. the acc. Due to gravity

d. the mass of the orbiting body

When a lift is moving upwards with uniform speed then its apparent weight will be a. greater than its real weight

b. less than its real weight

c. equal to its real weight

d. none

The velocity of the satellite with which a satellite revolves around the earth a. increases with the increase of its mass b. decreases with the increase in its mass c. remains the same with the increase in its mass d. none

5.

6.

The higher the satellite from the surface of the earth, the a. more the required speed

b. slower the required speed

c. either of them

d. none

The higher the satellite from the surface of the earth, the a. more time it will take to complete one revolution b. less time it will take to complete one revolution c. either of them

7.

Close orbiting satellite orbit the earth at a height of about a. 400 km

8.

d. none b. 200 km

c. 600 km

d. 800 km

Geo synchronous satellites are those satellite whose a. orbital motion is synchronized with earth b. spin motion is synchronized with earth c.either of them

(9) (a) (10) (a) (11).

d. none

Geo-stationary satellite completes one rotation around earth in. 3 hours (b) 6 hours (c) 12 hours (d) 12 hours Radius of geo-stationary orbit form center of earth is nearly. 42000 km (b) 36000 km (c) 24000 km (d) 18000 km One geo stationary satellite covers a longitude of a. 1200 b. 1800 c. 3600 d.

2700 (12). Height of geo stationary satellite above the equator is a. 36000 km b. 4200 km c. 3000 km d. 26000 km

(13). Minimum number of communication satellites required to cover the whole earth is a. 2 b. 3 c. 4 d. 5 (14) Einstein says that space time is curved specially near a. massive bodies b. light bodies c. space d. each body (15). Who says that gravity follows on inverse square law except in strong gravitational fields? a. Einstein b. Newton c. Plank d. Maxwell

Q.1 Explain why an object, orbiting the Earth, is said to be freely falling. Use your explanation to point out why objects appear weightless under certain circumstances. . Q.2 When mud flies off the tyre of a moving bicycle, in what direction does it fly? Explain. Q.3 A disc and a hoop start moving down from the top of an inclined plane at the same time. Which one will be moving faster on reaching the bottom? Q.4 Why does a diver change his body positions before diving in the pool? Q.5 Explain how much minimum number of geo-stationary satellites are required for global coverage of T.V. transmission. 6.What is difference between real and apparent weight. 7. derive the formula for orbital speed. 8.why we use microwaves for communications. 9.Define critical velocity. 10.on what factors orbital speed depends upon. 11.A man standing on the turntable raises his hands suddenly. What would happen?

Long questions 1. a. What is artificial gravity, how is it produced?. Calculate the relation of freq of rotation of satellite b. 2.An earth satellite is in circular orbit at a distance of 384,000 km from the earth’s surface. What is its period of one revolution in days? Take mass of the earth M = 6.0 x 10 24 kg and its radius R = 6400 km. 3.What is the least speed at which an aero plane can execute a vertical loop of 1.0 km radius so that there will be no tendency for the pilot to fall down at the highest point.

2.

a. What is geo stationary orbit? Calculate the radius of geo stationary orbit. b. The earth rotates on its axis once a day. Suppose, by some process the earth contracts so that its radius is only half as large as at present How fast will it be rotating then.? (For sphere I = 2/5 MR)2

3 .WRITE A NOTE ON EINSTIEN VIEW OF GRAVITATION. b..What is the least speed at which an aero plane can execute a vertical loop of 1.0 km radius so that there will be no tendency for the pilot to fall down at the highest point.