Question:
What are the factors the buoyant force depends on?
Answer:
1. The volume of the object immersed in the liquid.
2. The density of the liquid.
(Note: Buoyant force does not change with depth).
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.
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 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.
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.
What do you mean by acceleration due to gravity ?
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.
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 11.
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 12.
Calculate the value of acceleration due to gravity on Moon. Given mass of Moon =
kg, radius of Moon = 1740 km
Q 13.
Fill in the blanks :
Every object in the universe ________ other bodies.
Q 14.
Can you calculate density of Earth from Newton’s law of gravitation ?
Q 15.
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 16.
Fill in the blanks :
________ of an object is the force of gravity acting on it.
Q 17.
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 18.
Fill in the blanks :
Weight of an object is the product of ______ and ________.
Q 19.
Write the standard equations of motion when an object is thrown upwards with some initial velocity?
Q 20.
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 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.
Which force is responsible for tides in the ocean at night ?
Q 25.
Distinguish between gravitation and gravity.
Q 26.
Explain what is meant by ‘free fall’and acceleration due to gravity.
Q 27.
Who measured the value of G first time, experimentally?
Q 28.
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 29.
Does Law of gravitation obey Newton's third law of motion?
Q 30.
Fill in the blanks :
The average acceleration of free fall on the surface of earth is ______ .
Q 31.
You find your mass to be 42 kg on a weighing machine. Is your mass more or less than 42 kg?
Q 32.
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 33.
What is the importance of universal law of gravitation ?
Q 34.
Does Newton’s third law of motion apply to gravitational force ?
Q 35.
Fill in the blanks :
The value of
g ________ (increases/decreases) as we go upwards from the earth's surface.
Q 36.
An object moves in a circular motion due to centripetal force, acting towards the center. The moon also rotates around the earth? Does centripetal force acts on it? Why does the moon not fall on the earth?
OR
Q:If the moon attracts the earth, why does the earth not move towards the moon?
Q 37.
The Earth attracts an apple. Does the apple also attract the Earth? If it does, why does the Earth not move towards the apple?
Q 38.
What happens to 'g' experienced by a body when it moves up the earth's surface?
Q 39.
A stone is thrown vertically upward with an initial velocity of 40 m/s. Taking g = 10 m/s
2, find the maximum height reached by the stone. What is the net displacement and the total distance covered by the stone?
Q 41.
The tangential velocity of a planet or moon moving in a circle is at a right angle to ____________. (fill in the blank)
Q 42.
Fill in the blanks :
A body is said to be in _______ when only gravity acts on it.
Q 43.
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 44.
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 45.
Why does an object float or sink when placed on the surface of the water?
Q 46.
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 47.
Is the Archimedes principle applicable to gases?
Q 48.
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 49.
A ball of mass 4kg and density 4000 kgm
3 is completely immersed in water. Find the buoyant force acting on ball if the density of water is 10
3kg/m
3. (Take g = 10ms
-2)
Q 50.
A solid weighs 80g in air, 64g in water. Calculate the relative density of solid.
