What is the direction of acceleration due to gravity? Explain with an example.

Show that acceleration due to gravity at the surface of the moon is about one-sixth of that at the surface of the earth.

 A ball is dropped from a cliff. Find (a) its speed 2 seconds after it is dropped, (b) its speed when it has fallen through 78.4 m, (c) the time taken in falling through 78.4 m. 

 A stone is thrown upwards from the surface of the moon with a velocity of 19.6 m/s. {a) How much time will it take to attain the maximum height? (b) How high will it go?

A stone is dropped from a height of $2 \mathrm{m}$ from the surface of the earth.

(a) What will be its speed just before it hits the ground?

(b) How much time would it take to reach the ground?

(Given $g=9.8 \mathrm{m}/{\mathrm{s}}^2$)

Define mass and weight. What are their S.l. Units? Write any two differences between them.

What is universal law of gravitation? Explain how the force depends upon distance? What will happen to the force if
(i) the distance between two objects is doubled.
{ii) the distance between two objects is halved.

Deduce an expression for g for a body falling freely under earth's gravity. Hence, show that the value of g is independent of the mass of the falling body.