A stone is dropped from the adge ofg the roof, find
(i) How long does it take to fall 4.9 m?
(ii) How fast does it move at the end of that fall?
(iii) How fast does it move at the end of 7.9 metres?
(iv) What is its acceleration after 1 s and after 2s?

4

(a)

What are the differences between the mass of an object and its weight?

4

(a)

What happens to the force between two objects, if
(i) the mass of one object is doubled?
(ii) the distance between the objects is doubled and tripled?
(iii) the masses of both objects are doubled?

4

(a)

State any three differences between mass and weight.

4

(a)

(i) Prove that, if the earth attracts two bodies placed at the same distance from the centre of the earth with equal force, then their masses will be the same.
(ii) Mathematically express the acceleration due to gravity in terms of mass of the earth and radius of the earth.
(iii) Why is G called a universal constant?

4

(a)

(i) list two differences between thrust and pressure.
(ii) What is meant by 1 pascal and 1 newton? How will the pressure change, if area of contact is doubled?

4

(a)

(i) A steel needle sinks in water but a steel ship floats. Explain, how?
(ii) Why do you prefer a broad and thick handle of your suitcase?

4

(a)

(i) Enlist two forces which act on a body when it is immersed in a liquid. State the condition for a body require to float or sink in a liquid.
(ii) Why does an iron nail sink and a piece of wood floats? Explain, how?

4

(a)

(i) Define relative density. Give its mathematical form.
(ii) The mass of an iron cube having an edge length 1.5 em is 50 g. Find its density.
(iii) The volume of a 250 g sealed tin is 400 cubic cm. Find the density of the tin in g (cc)-1. State, if the object would sink or float in water

4

(a)

The radius of the earth at the poles is 6357 km and the radius at the equator is 6378 km. Calculate the percentage change in the weight of a body when it is taken from the equator to the poles.

4

(a)