A ball is thrown vertically upwards with a velocity of $49$ m/s. Calculate (ii) the total time it takes to return to the surface of the earth.
2.
A ball is thrown vertically upwards with a velocity of $49$ m/s. Calculate (i) the maximum height to which it rises,
3.
What do we call the gravitational force between the earth and an object?
4.
A ball thrown up vertically returns to the thrower after $6$ s. Find (a) the velocity with which it was thrown up,
5.
Gravitational force on the surface of the moon is only $\frac{1}{6}$ as strong as gravitational force on the earth. What is the weight in newtons of a $10$ kg object on the moon and on the earth?
6.
A stone is allowed to fall from the top of a tower $100$ m high and at the same time another stone is projected vertically upwards from the ground with a velocity of $25$ m/s. Calculate when and where the two stones will meet.
7.
Why does a block of plastic released under water come up to the surface of water?
8.
Gravitational force acts on all objects in proportion to their masses. Why then, a heavy object does not fall faster than a light object?
9.
In what direction does the buoyant force on an object immersed in a liquid act?
10.
A stone is thrown vertically upward with an initial velocity of $40$ m/s. Taking $g = 10$ m/s$^2$, find the maximum height reached by the stone. What is the net displacement and the total distance covered by the stone?
11.
A ball thrown up vertically returns to the thrower after $6$ s. Find (c) its position after $4$ s.
12.
What is the magnitude of the gravitational force between the earth and a $1$ kg object on its surface? (Mass of the earth is $6 \times 10^{24}$ kg and radius of the earth is $6.4 \times 10^{6}$ m.)
13.
Calculate the force of gravitation between the earth and the Sun, given that the mass of the earth = $6 \times 10^{24}$ kg and of the Sun = $2 \times 10^{30}$ kg. The average distance between the two is $1.5 \times 10^{11}$ m.
14.
A ball thrown up vertically returns to the thrower after $6$ s. Find (b) the maximum height it reaches, and
15.
What is the importance of universal law of gravitation?
16.
If the moon attracts the earth, why does the earth not move towards the moon?
17.
What happens to the force between two objects, if (ii) the distance between the objects is doubled and tripled?
18.
The earth and the moon are attracted to each other by gravitational force. Does the earth attract the moon with a force that is greater or smaller or the same as the force with which the moon attracts the earth? Why?
19.
What happens to the force between two objects, if (iii) the masses of both objects are doubled?
20.
Why will a sheet of paper fall slower than one that is crumpled into a ball?
