Question

Ryan International School, Ludhiana
Session: 2020-21
Ch. 10 Gravitation
Practice Worksheet
A Answer the following questions
1. A stone falling towards the earth also attracts the earth with same force. Is it true?
2. Derive relation between g and G.
3. Amit buys few grams of gold at poles as per the instructions of one of his friend. He
hands over the same when he met his friend at equator. Will the friend agree with the
weight of gold bought? If not, why?
4. Write two applications of Newton law of gravitation.
5. A ball is dropped from the top of tower 40 m high. What is the velocity when it has
covered 20m? What would be its velocity when it hits the ground? Take g=10ms
(Ans. V=20m/s, v=28.3m/s)
6. An object is thrown vertically upwards and rises to a height of 10m.Calculate
The velocity with which the object was thrown upwards.
Time taken by object to reach the highest point.(g=9.8 m/s-)
(Ans. 1. 14m/s 2. 1.43sec)​

Answer 1

Answer:

1 If we keep stone in space it will not exibhit any force. To fall the stone should need some force so in this case we cannot say that they having same forces.

2  G and g

In physics, G and g can be related mathematically as –

g=GM/R2

Where,

g is the acceleration due to the gravity of any massive body measured in m/s2.

G is the universal gravitational constant measured in Nm2/kg2.

R is the radius of the massive body measured in km.

M is the mass of the massive body measured in Kg

g Formula

According to the universal law of gravit,  

F=GMmR2 ————(1)

From Newton’s second law of motion we can write –

g=Fm ———–(2)

Substituting equation (1) in (2) we get-

g=GMmR2m

Thus, we arrive at the g formula in physics as –

⇒g=GMR2

Hope you understood the relation and conversion between G and g along with formula, definition, difference, and values.

Since the acceleration due to gravity is less at equator as compared to that at poles, the weight of the gold will be less at the equator than at the poles. Hence, Amit's friend won't agree with the weight of the gold bought since it would be less than what he is expecting.