Question:
The distance between two objects is doubled. What happens to gravitational force between them
Answer:
The gravitational force becomes (l/4)th.
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.
Fill in the blanks :
Every object in the universe ________ other bodies.
Q 6.
What is the value of ‘g’ at the centre of Earth ?
Q 7.
Which force is responsible for tides in the ocean at night ?
Q 8.
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 9.
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 10.
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 11.
What do you mean by acceleration due to gravity ?
Q 12.
Can you calculate density of Earth from Newton’s law of gravitation ?
Q 13.
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 14.
What do we call the gravitational force between the Earth and an object ?
Q 15.
State and explain universal law of gravitation given by Newton.What is the importance of this law
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.
Fill in the blanks :
________ of an object is the force of gravity acting on it.
Q 18.
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 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.
Who measured the value of G first time, experimentally?
Q 21.
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 22.
What is the importance of universal law of gravitation ?
Q 23.
What happens to 'g' experienced by a body when it moves up the earth's surface?
Q 24.
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 25.
Write the standard equations of motion when an object is thrown upwards with some initial velocity?
Q 26.
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 27.
What is the gravitational acceleration of a spaceship at a distance equal to two Earth’s radius from the centre of the Earth ?
Q 28.
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 29.
Fill in the blanks :
Heliocentric model was proposed by ______.
Q 30.
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 31.
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 32.
Is weight a scalar quantity?
Q 33.
Fill in the blanks :
The gravitational force between the earth and the object is generally called ____________.
Q 36.
Does value of ‘g’ vary from place to place on Earth ?
Q 37.
Fill in the blanks :
The value of
g at poles is ______ (lower/higher) than its value at the equator.
Q 38.
Why will a sheet of paper fall slower than one that is crumpled into a ball?
Q 39.
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 40.
Who explained the motion of planets around the Sun ?
Q 41.
Where is ‘g’greater, at poles or at equator ?
Q 42.
Where is ‘g' maximum, on the surface of Earth, above the surface or below the surface of Earth ?
Q 43.
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 44.
Fill in the blanks :
The value of
g on the earth's surface is ______.
Q 45.
What are Plimsoll Lines?
Q 46.
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 47.
Relative density of silver is 10.8. If the density of water is 10
3kg/m
3, find density of silver.
Q 48.
A force of 20 N acts upon a body whose weight is 9.8 N.What is the mass of the body and how much is its acceleration ?
Q 49.
State the universal law of gravitation.
Q 50.
What is value of ‘g’ on Earth ?
