9th Physics Unit 5 Test

Q: 1. Tick the correct answer.

1. Value of g on the surface of Venus is

• 73                 b. 1.62                   c. 25.94                 d. 8.87
• Does an apple attract the Earth towards it?
• Yes                   no                      c. none
• Moon complete its one revolution around the earth in
• 27 days             27.3 days             c. 18 days            d. 30 days
• Weight of a body is equal to the __________between the body and the earth
• Frictional force                  field strength                c. gravitational force       d. none
• Earth gravitational force of attraction vanishes at
• 6400km                              infinity                             c. 42300 km                    d. 1000km
• Value of g increase with the
• Increase with altitude                       b. Decrease with altitude
• Increase in mass of the body            d.  None of the above

Q: 2. Short questions

1. Explain how the value of g varies with altitude?
2. On what factors the orbital speed of a satellite depends?
3. What is a field force?
4. What is meant by gravitational field strength?
5. Define law of gravitation.
6. Why communication satellites are stationed at geostationary orbits?
7. Calculate the mass of earth, the acceleration due to gravity at an altitude 1000km. The value of g is 7.3ms^-2. The radius of the earth is 6400km.