Physics

Gravitation

Question:

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.

Answer:

(d)
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Gravitation

Q 1.

When a ball is thrown upwards, it falls back to the ground. Name the force which makes it fall.

Q 2.

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 3.

Two bodies A and B having masses 2 kg and 4 kg respectively are separated by 2 m.Where should a body of mass 1 kg be placed so that the gravitational force on this body due to bodies A and B is zero ?

Q 4.

A stone is thrown vertically upward with an initial velocity of 40 m/s.Taking g = 10 m/s2,find the maximum height reached by the stone.What is the net displacement and the total distance covered by the stone ?

Q 5.

Which force accelerates a body in free fall ?

Q 6.

Can you calculate mass of Earth from Newton’s law of gravitation ?

Q 7.

State and explain universal law of gravitation.What is its importance ?

Q 8.

Fill in the blanks :
The force which keeps the object moving in a circular path is called _____ force. It always acts towards the _____.

Q 9.

What is free fall?

Q 10.

What are the factors the buoyant force depends on?

Q 11.

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 12.

What is the source of centripetal force that a planet requires to revolve around the Sun ? On what factors does that force depend ?

Q 13.

Two objects of masses m1 and m2 having the same size are dropped simultaneously from heights h1 and h2 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 14.

What is the value of G (i) on Earth (ii) on Moon ?

Q 15.

Then why Is the Earth not seen moving towards the stone ?

Q 16.

What is the SI unit of mass ?

Q 17.

What is the weight of a body of mass 1 kg on Earth ?

Q 18.

What is inverse square rule ?

Q 19.

Name two applications of Newton’s law of gravitation.

Q 20.

Can a body have weight but no mass ?

Q 21.

A body weighs 10 kg on the surface of earth.What would be its mass and weight at the centre of earth ?

Q 22.

Distinguish between mass and weight.

Q 23.

On earth,value of G = 6.67x10-11N m2K g-2.What is its value on moon,where g is nearly 16th that of earth ?

Q 24.

Fill in the blanks :
The mass of an object _____ (varies/does not vary) on the earth as well as on the moon. But its weight is ______(same/different) on both places.

Q 25.

Fill in the blanks :
The value of g ________ (increases/decreases) as we go upwards from the earth's surface.

Q 26.

Fill in the blanks :
Weight of an object is the product of ______ and ________.

Q 27.

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 28.

Define 'g' or acceleration due to gravity? Does it depend on the mass of the body (near the surface of the earth)experiencing 'g'?

Q 29.

How does value of 'g' vary on the earth? What are the factors responsible for this?

Q 30.

Write the standard equations in the form when an object is dropped from a height?

Q 31.

A ball is thrown vertically upwards with a velocity of 49 m/s. Calculate(i) the maximum height to which it rises.(ii)the total time it takes to return to the surface of the earth.

Q 32.

A stone is thrown vertically upward with an initial velocity of 40 m/s. Taking g = 10 m/s2, find the maximum height reached by the stone. What is the net displacement and the total distance covered by the stone?

Q 33.

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 34.

A ball is thrown with some velocity 'u' m/s. Show that under free fall, it will fall the ground with same velocity.

Q 35.

Name the scientist who identified the relation about force of gravitation. Name the law.

Q 36.

Fill in the blanks :
The acceleration which causes changes only in direction of the velocity of a body is called __________ and it is always directed ___________ the circle.

Q 37.

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 38.

Define 1 Pascal.

Q 39.

Why will a sheet of paper fall slower than one that is crumpled into a ball?

Q 40.

The volume of 50 g of a substance is 20 cm3. If the density of water is 1 g cm-3, will the substance float or sink?

Q 41.

You find your mass to be 42 kg on a weighing machine. Is your mass more or less than 42 kg?

Q 42.

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 43.

The weight of an empty glass is 1 N. When completely filled with water, the glass weighs 4 N. If you now throw the water away and fill the glass partly with sand, the weight becomes 4 N. If the rest of the glass is now filled up with water, the weight becomes 6 N. What is the relative density of sand?

Q 44.

Relative density of silver is 10.8. If the density of water is 103kg/m3, find density of silver.

Q 45.

A ball of mass 4kg and density 4000 kgm3 is completely immersed in water. Find the buoyant force acting on ball if the density of water is 103kg/m3. (Take g = 10ms-2)

Q 46.

The volume of 50g of a substance is 20 cm3. If the density of water is 1g/cm3, will the substance float or sink?

Q 47.

A solid weighs 80g in air, 64g in water. Calculate the relative density of solid.

Q 48.

The mass of Sun is 2x1030 kg and mass of Earth is 6x1024 kg. If the distance between the centres of Sun and Earth is 1.5x1080 km,calculate the force of gravitation between them.

Q 49.

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 50.

If the distance of Earth from the Sun were half the present value,how many days will make one year ?