Question:
What do you mean by free fall ?
Answer:
All objects falling towards Earth under the action of gravitational force of Earth alone are said to be in free fall.
Gravitation
Q 1.
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 2.
State Kepler’s Laws of planetary motion. How did Newton guess inverse square law ?
Q 3.
What do we call the gravitational force between the Earth and an object ?
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.
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 6.
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 7.
Can you calculate density of Earth from Newton’s law of gravitation ?
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.
What is the value of ‘g’ at the centre of Earth ?
Q 11.
Why do sewing needles and all pins have a sharp pointed tip?
Q 12.
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 13.
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 14.
Calculate the value of acceleration due to gravity on Moon. Given mass of Moon =
kg, radius of Moon = 1740 km
Q 15.
Fill in the blanks :
________ of an object is the force of gravity acting on it.
Q 16.
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 17.
Write the standard equations of motion when an object is thrown upwards with some initial velocity?
Q 18.
Fill in the blanks :
Weight of an object is the product of ______ and ________.
Q 19.
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 20.
The distance of planet Jupiter from the sun is 5-2 times that of Earth.Find the period of revolution of Jupiter around sun.
Q 21.
What is the gravitational acceleration of a spaceship at a distance equal to two Earth’s radius from the centre of the Earth ?
Q 22.
Can a body have weight but no mass ?
Q 23.
Fill in the blanks :
The gravitational force between the earth and the object is generally called ____________.
Q 24.
Who measured the value of G first time, experimentally?
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.
Which force is responsible for tides in the ocean at night ?
Q 27.
Distinguish between gravitation and gravity.
Q 28.
Explain what is meant by ‘free fall’and acceleration due to gravity.
Q 29.
Fill in the blanks :
The value of
g on the earth's surface is ______.
Q 30.
How is gravitational force of attraction between two bodies affected if(i) Mass of both bodies is doubled.(ii) Distance between them is halved.
Q 31.
Does Law of gravitation obey Newton's third law of motion?
Q 32.
What happens to 'g' experienced by a body when it moves up the earth's surface?
Q 33.
Define weight? How it is related to mass?
Q 34.
Write the standard equations in the form when an object is dropped from a height?
Q 35.
Fill in the blanks :
The average acceleration of free fall on the surface of earth is ______ .
Q 36.
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 37.
Why does an object float or sink when placed on the surface of the water?
Q 38.
You find your mass to be 42 kg on a weighing machine. Is your mass more or less than 42 kg?
Q 39.
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 40.
Write the formula to find the magnitude of the gravitational force between the Earth and an object on the surface of the Earth.
Q 41.
The Earth and the Moon are attracted to each other by gravitational force. Does the Earth attract the Moon with a force that is greater or smaller or the same as the force with which the Moon attracts the Earth ? Why ?
Q 42.
What is the importance of universal law of gravitation ?
Q 43.
What is the usual shape of orbits of planets around the Sun ?
Q 44.
Does Newton’s third law of motion apply to gravitational force ?
Q 45.
Does value of ‘g’ vary from place to place on Earth ?
Q 46.
What is the SI unit of mass ?
Q 47.
Can a body have mass but no weight ?
Q 48.
State and explain universal law of gravitation given by Newton.What is the importance of this law
Q 49.
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 50.
Fill in the blanks :
Geocentric model i.e. the Earth is the orbital centre of all celestial bodies was proposed by _____.
