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.
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 3.
Can you calculate density of Earth from Newton’s law of gravitation ?
Q 4.
What is the value of ‘g’ at the centre of Earth ?
Q 5.
What do you mean by acceleration due to gravity ?
Q 6.
What do we call the gravitational force between the Earth and an object ?
Q 7.
Fill in the blanks :
Weight of an object is the product of ______ and ________.
Q 8.
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 9.
Why do sewing needles and all pins have a sharp pointed tip?
Q 10.
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 11.
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 12.
Fill in the blanks :
Every object in the universe ________ other bodies.
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.
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 15.
Is weight a scalar quantity?
Q 16.
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 17.
Calculate the value of acceleration due to gravity on Moon. Given mass of Moon =
kg, radius of Moon = 1740 km
Q 18.
Fill in the blanks :
The gravitational force between the earth and the object is generally called ____________.
Q 19.
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 20.
What are the Kepler Laws that govern the motion of the planets?
Q 21.
Mass of an object is 10 kg. What is its weight on the Earth? (g = 9.8 m/s
2.)
Q 23.
Fill in the blanks :
________ of an object is the force of gravity acting on it.
Q 24.
Fill in the blanks :
The SI unit of mass is ______.
Q 25.
Fill in the blanks :
It is the ____________ of the earth, which holds our atmosphere in place.
Q 26.
Why does an object float or sink when placed on the surface of the water?
Q 27.
The volume of a 500 g sealed packet is 350 cm
3. Will the packet float or sink in water if the density of water is 1 g cm
-3? What will be the mass of the water displaced by this packet?
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.
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 30.
What are the differences between the mass of an object and its weight ?
Q 31.
Who explained the motion of planets around the Sun ?
Q 32.
Can a body have weight but no mass ?
Q 33.
On earth,value of G =
.What is its value on moon,where g is nearly
th that of earth ?
Q 34.
Fill in the blanks :
Heliocentric model was proposed by ______.
Q 35.
Fill in the blanks :
The SI unit of weight is _____.
Q 36.
What was heliocentric theory? Who proposed this?
Q 37.
State the universal law of gravitation.
Q 38.
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 40.
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 41.
Define weight? How it is related to mass?
Q 42.
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 43.
Name the scientist who identified the relation about force of gravitation. Name the law.
Q 44.
Is mass a scalar quantity?
Q 46.
Fill in the blanks :
Motion of body with constant speed in a circular path is called ______________.
Q 47.
Fill in the blanks :
A body is said to be in _______ when only gravity acts on it.
Q 48.
What are Plimsoll Lines?
Q 49.
Why will a sheet of paper fall slower than one that is crumpled into a ball?
Q 50.
The volume of 50 g of a substance is 20 cm
3. If the density of water is 1 g cm
-3, will the substance float or sink?
