Question:
On earth,value of G = .What is its value on moon,where g is nearly th that of earth ?
Answer:
Value of G is same on moon as on earth,because G is a universal gravitational constant.
Gravitation
Q 1.
Is mass a scalar quantity?
Q 2.
Can you calculate mass of Earth from Newton’s law of gravitation ?
Q 3.
Explain what is meant by ‘free fall’and acceleration due to gravity.
Q 4.
Two objects of masses
having the same size are dropped simultaneously from heights
respectively.Find out the ratio of time they would take in reaching the ground.Will this ratio remain the same if (1) one of the objects is hollow and the other one is solid and (ii) both of them are hollow,size remaining the same in each case.Give reason.
Q 5.
What is the SI unit of weight ?
Q 6.
Comment on application of Newton’s third law of motion to gravitation.Illustrate by examples.
Q 7.
Who measured the value of G first time, experimentally?
Q 9.
Can you calculate density of Earth from Newton’s law of gravitation ?
Q 10.
Write the standard equations of motion when an object is thrown upwards with some initial velocity?
Q 11.
The distance between two objects is doubled. What happens to gravitational force between them
Q 12.
Does gravitational force between two objects depend on medium between them ?
Q 13.
A stone falling towards Earth also attracts the Earth with the same force.Is it true ?
Q 14.
Distinguish between gravitation and gravity.
Q 15.
Write down the equations of motion of objects under the influence of gravitational force of Earth.Explain the meaning of the symbols used.
Q 16.
Distinguish between mass and weight.
Q 17.
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 18.
Fill in the blanks :
Heliocentric model was proposed by ______.
Q 20.
When a ball is thrown upwards, it falls back to the ground. Name the force which makes it fall.
Q 21.
As you climb up a mountain, your ears “pop” because of the changes in atmospheric pressure. In which direction, outward or inward, does your eardrum move when you climb up?
Q 22.
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 23.
What is value of ‘g’ on Earth ?
Q 24.
How are gravitation and gravity related ?
Q 25.
State and explain universal law of gravitation.What is its importance ?
Q 26.
Fill in the blanks :
According to the Heliocentric theory, the _____ is at centre and _______ move around it.
Q 27.
Fill in the blanks :
Kepler's Law of ______ states that a line that connects a planet to the Sun sweeps out equal ______ in the plane of the planet's orbit in _____time intervals.
Q 28.
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 29.
What was geocentric model? Who proposed this theory?
Q 30.
Why is G called the Universal Constant?
Q 31.
A ball is thrown up and is caught by the player after 4 seconds.How high did it go and with what velocity was it thrown? How far below the ball will be from its highest point after 3 seconds from start?
Q 32.
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 33.
What do you mean by Thrust or Buoyant force?
Q 34.
The following figure shows four containers containing a liquid at the same height. Rank them according to the pressure exerted by the liquid on the bottom of the containers in ascending order.

a. 1, 2, 3, 4 b. 4. 3, 1, 2 c. 3, 4, 1, 2 d. same pressure in each case.
Q 35.
Why do sewing needles and all pins have a sharp pointed tip?
Q 36.
A stone drops from the edge of the roof.It passes a window 2 m high in 0.1 s.How far is the roof above the top of the window
Q 37.
Mass of an object is 10 kg. What is its weight on Earth ?
Q 38.
State the universal law of gravitation.
Q 39.
What do you mean by acceleration due to gravity ?
Q 40.
How does the force of gravitation between two objects change when the distance between them is reduced to half ?
Q 41.
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 42.
What is the usual shape of orbits of planets around the Sun ?
Q 43.
A body is just dropped from a height What is its initial velocity ?
Q 44.
Compare gravitational force between light objects and heavy objects.
Q 45.
Fill in the blanks :
The mass of the earth is ________ kg.
Q 46.
Fill in the blanks :
The value of
g at poles is ______ (lower/higher) than its value at the equator.
Q 47.
Fill in the blanks :
The value of G was found out by _______ by using a ________.
Q 48.
Why does one feel giddy while moving on a merry go round ?
Q 49.
Fill in the blanks :
________ of an object is the force of gravity acting on it.
Q 50.
Fill in the blanks :
The SI unit of mass is ______.