Question:
Why is G called the Universal Constant?
Answer:
At any place in the universe and at any time, the value of G is found to be constant for any two bodies. Thus G is called the universal constant of gravitation.
It is defined as force of attraction acting between two objects of mass 1 kg each placed at a distance of 1 m.
Mathematically, G = F.d2/m1m2
Thus the SI unit of the universal constant of gravitation is Nm2/kg2.
The value of G is 6.67 × 10-11 Nm2/kg2
Gravitation
Q 1.
State Kepler’s Laws of planetary motion. How did Newton guess inverse square law ?
Q 2.
Why do sewing needles and all pins have a sharp pointed tip?
Q 3.
Calculate the value of acceleration due to gravity on Moon. Given mass of Moon =
kg, radius of Moon = 1740 km
Q 4.
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 5.
What is the value of ‘g’ at the centre of Earth ?
Q 6.
Fill in the blanks :
Every object in the universe ________ other bodies.
Q 7.
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 8.
Which force is responsible for tides in the ocean at night ?
Q 9.
What do you mean by acceleration due to gravity ?
Q 10.
Can you calculate density of Earth from Newton’s law of gravitation ?
Q 11.
State and explain universal law of gravitation given by Newton.What is the importance of this law
Q 12.
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 13.
What do we call the gravitational force between the Earth and an object ?
Q 14.
Fill in the blanks :
________ of an object is the force of gravity acting on it.
Q 15.
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 16.
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 17.
The mass of Earth is
kg and that of moon is
kg. If the distance between the Earth and the Moon is
km, calculate the force exerted by Earth on the Moon. Given G =
.
Q 18.
Who measured the value of G first time, experimentally?
Q 19.
Calculate the force of gravitation between two objects of masses 80 kg and 1200 kg kept at a distance of 10 m from eachother.Given, G =
/
.
Q 20.
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 21.
What is the importance of universal law of gravitation ?
Q 22.
Gravitational force acts on all objects in proportion to their masses.Why then,a heavy object does not fall faster than a light object ?
Q 23.
Fill in the blanks :
Assuming negligible air drag, if a steel ball and a table tennis ball are dropped from a height of 100 metres, both will reach the ground at ________ time(s). (same/different)
Q 24.
What happens to 'g' experienced by a body when it moves up the earth's surface?
Q 25.
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
Q 26.
Calculate the force of gravitation between the earth and the Sun, given that the mass of the earth = 6 × 10
24 kg and of the Sun = 2 × 10
30 kg. The average distance between the two is 1.5 × 10
11 m.
Q 27.
Fill in the blanks :
Heliocentric model was proposed by ______.
Q 28.
What is the gravitational acceleration of a spaceship at a distance equal to two Earth’s radius from the centre of the Earth ?
Q 29.
Write the standard equations of motion when an object is thrown upwards with some initial velocity?
Q 31.
Is weight a scalar quantity?
Q 33.
Where is ‘g' maximum, on the surface of Earth, above the surface or below the surface of Earth ?
Q 34.
Fill in the blanks :
The gravitational force between the earth and the object is generally called ____________.
Q 35.
A car falls off a ledge and drops to the ground in 0.5 s.Let g =
(for simplifying the calculations).
(i) What is its speed on striking the ground ?
(ii) What is its average speed during 0.5 s ?
(iii) How high is the ledge from the ground ?
Q 36.
Fill in the blanks :
The value of
g on the earth's surface is ______.
Q 37.
Fill in the blanks :
Weight of an object is the product of ______ and ________.
Q 38.
Fill in the blanks :
The value of G was found out by _______ by using a ________.
Q 39.
Fill in the blanks :
The force of gravity _________ with altitude. It also varies on the surface of the earth, _________ from poles to the equator.
Q 40.
Why is it difficult to hold a school bag having a strap made of a thin and strong string?
Q 41.
A stone falling towards Earth also attracts the Earth with the same force.Is it true ?
Q 42.
Then why Is the Earth not seen moving towards the stone ?
Q 43.
What is the SI unit of weight ?
Q 44.
A body weighs 10 kg on the surface of earth.What would be its mass and weight at the centre of earth ?
Q 45.
State and explain universal law of gravitation.What is its importance ?
Q 46.
Fill in the blanks :
According to the Heliocentric theory, the _____ is at centre and _______ move around it.
Q 47.
Fill in the blanks :
The force which keeps the object moving in a circular path is called _____ force. It always acts towards the _____.
Q 48.
Fill in the blanks :
When objects of different masses and sizes are dropped from same height would reach the ground at ______ (same time/different times), considering negligible air resistance.
Q 49.
Fill in the blanks :
The value of
g ________ (increases/decreases) as we go downwards from the earth's surface.
Q 50.
An object moves in a circular motion due to centripetal force, acting towards the center. The moon also rotates around the earth? Does centripetal force acts on it? Why does the moon not fall on the earth?
OR
Q:If the moon attracts the earth, why does the earth not move towards the moon?
