Chapter –Gravitation
1 – Mark Questions
1. What do you mean by free fall?
2. Name the scientist who estimated G.
3. What is the cause of tides in oceans?
4. What is thrust? Give its SI unit.
5. Define Relative density. What is its SI unit?
6. Relative density of gold is 19.3. What does this indicate?
7. State universal law of gravitation.
8. Express how ‘g’ and ‘G’ related.
9. Are ‘g’ and ‘G’ universal constant?
10. What is the mass of a body of 600N weight on the surface of earth?
11. Can a body have mass but no weight?
12. Why do needles have sharp ends?
13. Define buoyancy.
14. What is (i) lactometer (ii) hydrometer?
15. Where is the value of weight of a body (a) maximum and (b) minimum at the surface of the earth?
16. Name the force experienced by the body when it is immersed in a liquid?
17. The density of a substance is 840kg/m3. What will be its density?
18. What is the value of universal gravitational constant?
19. Define pressure. Write its SI unit.
20. State Archimedes principle.
2 – Mark Questions
1. Show that the acceleration due to gravity on the surface of the moon is 1/6th of its value on the surface of the
earth.
2. Give reason for the variation of acceleration due to gravity at the equator and the poles.
3. Differentiate between mass and weight.
4. If the force of earth on moon suddenly vanishes, what will be the path of the moon? Give reason.
5. Estimate the acceleration of earth due to the force exerted by a 10 kg apple (Me = 6 X 1024 kg)
6. Two equal masses separated by a distance experiences a force at ‘F’ Newton. If the masses are doubled, find the
change in separation required to maintain same force.
7. A stone takes 4s to hit the ground, from the top of a building when dropped. What is the height from where it
falls?
8. If two forces in the ratio 5 : 7 act on two areas in the ratio 4 : 5, find the ratio of pressure exerted.
9. Why do tractors have broad tyres?
10. Write two applications of Archimedes’ principle.
11. Derive relation between acceleration due to gravity and universal gravitational constant.
12. Explain why it is easier to cut an apple with a sharp knife?
13. Explain why a ship made of iron floats on water but an iron needle sinks.
14. Explain why a mug feels lighter inside water.
15. Define density. Is density and relative density are same?
3 – Mark Questions
1. Two masses m1 and m2 are separated by a distance r. Find:
(a) The ratio of the forces acting on each of them,
(b) Ratio of their acceleration and
20
(c) If m1 = 10 m2, which mass will be seen to move. Why?
2. A body is thrown vertically upwards and rises to a height of 10m. Calculate (i) the velocity with which the body
was thrown upwards and (ii) the time taken by the body to reach the highest point.
3. A stone is dropped from the top of a 40 m high tower. Calculate its speed after 2 s also find the speed with which
the stone strikes the ground. (Take g = 10ms-2)
4. Calculate the mass of earth, using the following values. Radius of earth = 6 X 103 km, g = 9.8 ms-2,
G= 6.67 X 10-11 Nm2kg-2.
5. The pressure exerted by the weight of a cubical block of side 3 cm on the surface is 5Pa. Calculate the Force on
the block.
6. A sealed cane of mass 600 g has a volume of 500 cm3. Will this cane sink in water?