Question:
Distinguish between gravitation and gravity.
Answer:
Refer to Arts 3.2 and 3.10,Pages 141 and 159.
Gravitation
Q 1.
State Kepler’s Laws of planetary motion. How did Newton guess inverse square law ?
Q 2.
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 3.
Calculate the value of acceleration due to gravity on Moon. Given mass of Moon =
kg, radius of Moon = 1740 km
Q 4.
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 5.
Why do sewing needles and all pins have a sharp pointed tip?
Q 6.
Which force is responsible for tides in the ocean at night ?
Q 7.
What is the value of ‘g’ at the centre of Earth ?
Q 8.
Fill in the blanks :
Every object in the universe ________ other bodies.
Q 9.
What do you mean by acceleration due to gravity ?
Q 10.
Fill in the blanks :
________ of an object is the force of gravity acting on it.
Q 11.
Can you calculate density of Earth from Newton’s law of gravitation ?
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.
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 14.
Who measured the value of G first time, experimentally?
Q 15.
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 16.
State and explain universal law of gravitation given by Newton.What is the importance of this law
Q 17.
Why is G called the Universal Constant?
Q 18.
The tangential velocity of a planet or moon moving in a circle is at a right angle to ____________. (fill in the blank)
Q 19.
State the universal law of gravitation.
Q 20.
What is the SI unit of weight ?
Q 22.
Loaded test-tube placed in pure milk sinks to a certain mark (M). Now some water is mixed with the milk. Will the test tube sink more or less? Explain.
Q 23.
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 24.
What is the source of centripetal force that a planet requires to revolve around the Sun ? On what factors does that force depend ?
Q 25.
Which force accelerates a body in free fall ?
Q 26.
Does Newton’s third law of motion apply to gravitational force ?
Q 27.
What is value of ‘g’ on Earth ?
Q 28.
Fill in the blanks :
Acceleration due to gravity (g) is _______ (dependent/independent) of mass.
Q 29.
Does the force of attraction between two objects depend on the properties of intervening medium?
Q 31.
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?
Q 33.
Is weight a scalar quantity?
Q 34.
Fill in the blanks :
The acceleration which causes changes only in direction of the velocity of a body is called __________ and it is always directed ___________ the circle.
Q 35.
Relative density of silver is 10.8. If the density of water is 10
3kg/m
3, find density of silver.
Q 36.
The gravitational force between two objects is 100 N. How should the distance between these objects be changed so that force between them becomes 50 N ?
Q 37.
Two bodies A and B having masses 2 kg and 4 kg respectively are separated by 2 m.Where should a body of mass 1 kg be placed so that the gravitational force on this body due to bodies A and B is zero ?
Q 38.
What is the importance of universal law of gravitation ?
Q 39.
What is the acceleration of free fall ?
Q 40.
A stone is thrown vertically upward with an initial velocity of 40 m/s.Taking g =
,find the maximum height reached by the stone.What is the net displacement and the total distance covered by the stone ?
Q 41.
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 42.
Where is ‘g’greater, at poles or at equator ?
Q 43.
Name two applications of Newton’s law of gravitation.
Q 44.
Can a body have weight but no mass ?
Q 45.
Distinguish between mass and weight.
Q 46.
Fill in the blanks :
The force which keeps the object moving in a circular path is called _____ force. It always acts towards the _____.
Q 47.
Fill in the blanks :
The value of Universal Gravitation constant (G) is ________ Nm
2kgs
-2.
Q 48.
Fill in the blanks :
The mass of an object _____ (varies/does not vary) on the earth as well as on the moon. But its weight is ______(same/different) on both places.
Q 49.
What was geocentric model? Who proposed this theory?
Q 50.
What are the Kepler Laws that govern the motion of the planets?
