Question:
What is the value of G (i) on Earth (ii) on Moon ?
Answer:
G = 6.67 x .
The value is the same on Earth and on Moon.
Gravitation
Q 1.
State Kepler’s Laws of planetary motion. How did Newton guess inverse square law ?
Q 2.
Calculate the force of gravitation between the Earth and the Sun,given that the mass of the Earth =
kg and mass of the Sun =
kg. The average distance between the two is
m.
Q 3.
What do we call the gravitational force between the Earth and an object ?
Q 4.
Can you calculate density of Earth from Newton’s law of gravitation ?
Q 5.
In Fig.,the line that joins a planet to the sun sweeps out areas
,
in time intervals 6 weeks,3 weeks and 2 weeks respectively.How are
,
realted ?
Q 6.
Why do sewing needles and all pins have a sharp pointed tip?
Q 7.
Is weight a scalar quantity?
Q 8.
What is the value of ‘g’ at the centre of Earth ?
Q 9.
What do you mean by acceleration due to gravity ?
Q 10.
At what height above the surface of the earth, the value of 'g' becomes 64% of its value at the surface of the earth. Take radius of the earth = 6400 km.
Q 11.
Suppose a planet exists whose mass and radius both,are half those of Earth.Calculate the acceleration due to gravity on the surface of this planet.
Q 12.
Fill in the blanks :
Weight of an object is the product of ______ and ________.
Q 13.
The distance between two objects is doubled. What happens to gravitational force between them
Q 14.
Two stones A and B are dropped from a multistoried building. A is dropped from 100 m and after some time B is dropped from 50 m height. Both of them reach the earth at the same time. Will they have equal velocity while reaching the ground ? Calculate and find out the answer (take g =10 m/s
2).
Q 15.
Who gave three laws of planetary motion ?
Q 16.
Can a body have weight but no mass ?
Q 17.
Fill in the blanks :
Geocentric model i.e. the Earth is the orbital centre of all celestial bodies was proposed by _____.
Q 18.
Who measured the value of G first time, experimentally?
Q 19.
What is the gravitational force between the Earth and a body called? In which direction does it occur?
Q 20.
Fill in the blanks :
Every object in the universe ________ other bodies.
Q 21.
Fill in the blanks :
The gravitational force between the earth and the object is generally called ____________.
Q 22.
The volume of 50 g of a substance is 20 cm
3. If the density of water is 1 g cm
-3, will the substance float or sink?
Q 23.
What is the gravitational acceleration of a spaceship at a distance equal to two Earth’s radius from the centre of the Earth ?
Q 24.
A particle is dropped from a tower 180 m high.How long does it take to reach the ground ? What is the velocity when it touches the ground ? Take g =
Q 25.
A ball is thrown up with a speed of 15 m/s.How high will it go before it begins to fall ? Take g=
Q 26.
Fill in the blanks :
Heliocentric model was proposed by ______.
Q 27.
(a) What is the relationship between g and G?
(b) Show mathematically whether g (acceleration due to gravity on the earth) depends on the mass of the object itself or not.
(c) Show that for a given location on the surface of the earth g is almost constant.
Q 28.
Define weight? How it is related to mass?
Q 29.
Mass of an object is 10 kg. What is its weight on the Earth? (g = 9.8 m/s
2.)
Q 30.
Fill in the blanks :
The SI unit of mass is ______.
Q 31.
Why is it difficult to hold a school bag having a strap made of a thin and strong string?
Q 32.
You find your mass to be 42 kg on a weighing machine. Is your mass more or less than 42 kg?
Q 33.
If the distance between two masses is increased by a factor of 4,by what factor would the mass of one of them have to be altered to maintain the same gravitational force ?
Q 34.
A boy on a clif£ 49 m high drops a stone.One second later,he throws a second stone after the first.They both hit the ground at the same time. With what speed did he throw the second stone ?
Q 35.
Calculate the value of acceleration due to gravity on Moon. Given mass of Moon =
kg, radius of Moon = 1740 km
Q 36.
State the universal law of gravitation.
Q 37.
How does the force of gravitation between two objects change when the distance between them is reduced to half ?
Q 38.
What is the acceleration of free fall ?
Q 39.
Which force is responsible for tides in the ocean at night ?
Q 40.
Does Newton’s third law of motion apply to gravitational force ?
Q 41.
A body is just dropped from a height What is its initial velocity ?
Q 42.
What is the weight of a body of mass 1 kg on Earth ?
Q 43.
Why don’t two objects move towards each other due to gravitational pull between them ?
Q 44.
Can a body have mass but no weight ?
Q 45.
What is the relation between g and G ?
Q 46.
Distinguish between gravitation and gravity.
Q 47.
Write down the equations of motion of objects under the influence of gravitational force of Earth.Explain the meaning of the symbols used.
Q 48.
Define g and G.Establish relation between them.
Q 49.
Whenever a body is thrown up with a certain velocity,the upward motion is opposed by gravitational pull of earth and also by the resistance of air.
Therefore, velocity of the body goes on decreasing. When this velocity becomes zero,the body cannot rise further.It has attained,what is called ‘maximum height’.From this height,the body begins to fall downwards under the action of gravity.
Read the above passage and answer the following questions:
(i) At the highest point,what are the velocity and acceleration of the body?
(ii) What is the maximum height attained by a body thrown upwards with a velocity of 19.6 m/s ? Take g =
.
(iii) What values in life do you learn from this concept ?
Q 50.
Fill in the blanks :
The force of attraction between two objects is ______ proportional to the product of their masses and _____ proportional to the square of a distance between them.
