Question:
What are the differences between the mass of an object and its weight ?
Answer:
The differences between mass and weight of an object are tabulated below :
| Mass | Weight |
|---|
1.Mass of an object is the quantity of matter contained in it.
2. Mass is a scalar.
3. SI unit of mass is kilogram.
4. Mass of an object is always constant.
5. Mass of an object is never zero. | 1. Weight of an object is the force with which it is attracted towards the centre of Earth.
2. Weight is a vector.
3. SI unit of weight is newton.
4. Weight of an object varies from place to place due to variation in g.
5. Weight of an object is zero at the centre of Earth. |
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.
Can you calculate density of Earth from Newton’s law of gravitation ?
Q 5.
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 6.
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 7.
Fill in the blanks :
________ of an object is the force of gravity acting on it.
Q 8.
What is the value of ‘g’ at the centre of Earth ?
Q 9.
Why do sewing needles and all pins have a sharp pointed tip?
Q 10.
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 11.
What do you mean by acceleration due to gravity ?
Q 12.
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 13.
Fill in the blanks :
Every object in the universe ________ other bodies.
Q 14.
Calculate the value of acceleration due to gravity on Moon. Given mass of Moon =
kg, radius of Moon = 1740 km
Q 15.
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 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.
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 19.
What is the gravitational acceleration of a spaceship at a distance equal to two Earth’s radius from the centre of the Earth ?
Q 20.
Fill in the blanks :
Weight of an object is the product of ______ and ________.
Q 21.
Fill in the blanks :
The gravitational force between the earth and the object is generally called ____________.
Q 22.
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 23.
Does Newton’s third law of motion apply to gravitational force ?
Q 24.
Distinguish between gravitation and gravity.
Q 25.
Explain what is meant by ‘free fall’and acceleration due to gravity.
Q 26.
What are Plimsoll Lines?
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.
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 29.
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 30.
Which force revolves Moon around Earth ?
Q 31.
State and explain universal law of gravitation.What is its importance ?
Q 32.
Does Law of gravitation obey Newton's third law of motion?
Q 33.
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 34.
A force of 200 N acts on a surface of area 10 cm
2. Calculate thrust and pressure. How much the pressure changes if the area of contact increases to 50 cm
2.
Q 35.
What is the source of centripetal force that a planet requires to revolve around the Sun ? On what factors does that force depend ?
Q 36.
What is the value of G (i) on Earth (ii) on Moon ?
Q 37.
Which force is responsible for tides in the ocean at night ?
Q 38.
A body is just dropped from a height What is its initial velocity ?
Q 39.
How are gravitation and gravity related ?
Q 40.
On earth,value of G =
.What is its value on moon,where g is nearly
th that of earth ?
Q 41.
Fill in the blanks :
The value of
g ________ (increases/decreases) as we go downwards from the earth's surface.
Q 42.
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 43.
Define weight? How it is related to mass?
Q 44.
A ball is thrown upwards from the ground of a tower with a speed of 20 m/s. There is a window in the tower at the height of 15m from ground. How many times and when will the ball pass the window? (g = 10 m/s
2)
Q 45.
Name the scientist who identified the relation about force of gravitation. Name the law.
Q 46.
Fill in the blanks :
All other variables remaining constant, the force of gravitation is ________ proportional to the square of distance between the two objects.
Q 47.
Fill in the blanks :
The average acceleration of free fall on the surface of earth is ______ .
Q 48.
You find your mass to be 42 kg on a weighing machine. Is your mass more or less than 42 kg?
Q 49.
A solid weighs 80g in air, 64g in water. Calculate the relative density of solid.
Q 50.
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 ?
