Question:
Which force accelerates a body in free fall ?
Answer:
The force of gravity of Earth.
Gravitation
Q 1.
State Kepler’s Laws of planetary motion. How did Newton guess inverse square law ?
Q 2.
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 3.
Calculate the value of acceleration due to gravity on Moon. Given mass of Moon =
kg, radius of Moon = 1740 km
Q 4.
What is the value of ‘g’ at the centre of Earth ?
Q 5.
Why do sewing needles and all pins have a sharp pointed tip?
Q 6.
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 7.
Which force is responsible for tides in the ocean at night ?
Q 8.
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 9.
Fill in the blanks :
Every object in the universe ________ other bodies.
Q 10.
Can you calculate density of Earth from Newton’s law of gravitation ?
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.
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 13.
What do you mean by acceleration due to gravity ?
Q 14.
What do we call the gravitational force between the Earth and an object ?
Q 15.
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 16.
Who measured the value of G first time, experimentally?
Q 17.
What is the importance of universal law of gravitation ?
Q 18.
Fill in the blanks :
________ of an object is the force of gravity acting on it.
Q 19.
What is value of ‘g’ on Earth ?
Q 20.
A body is projected upwards. What is its velocity at maximum height
Q 21.
State and explain universal law of gravitation given by Newton.What is the importance of this law
Q 22.
Mass of an object is 10 kg. What is its weight on the Earth? (g = 9.8 m/s
2.)
Q 23.
Calculate the force of gravitation between two objects of masses 80 kg and 1200 kg kept at a distance of 10 m from eachother.Given, G =
/
.
Q 24.
Distinguish between mass and weight.
Q 25.
Fill in the blanks :
Universal gravitational constant G = _____________.
Q 26.
Why will a sheet of paper fall slower than one that is crumpled into a ball?
Q 27.
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 28.
A stone is thrown vertically upward with an initial velocity of 40 m/s.Taking g =
,find the maximum height reached by the stone.What is the net displacement and the total distance covered by the stone ?
Q 29.
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 30.
Write the standard equations in the form when an object is dropped from a height?
Q 31.
What are Plimsoll Lines?
Q 32.
Why does a block of plastic released under water come up to the surface of the water?
Q 33.
An object is thrown vertically upwards and rises to a height of 10 m. Calculate (i) the velocity with which the object was thrown upwards and (ii) the time taken by the object to reach the highest point.
Q 34.
State the universal law of gravitation.
Q 35.
What do you mean by free fall ?
Q 36.
What is the magnitude of the gravitational force between the Earth and a 1 kg on its surface ? (Mass of the Earth Is
kg and radius of the Earth is
m.)
Q 37.
What is the value of G (i) on Earth (ii) on Moon ?
Q 38.
Which force revolves Moon around Earth ?
Q 39.
Then why Is the Earth not seen moving towards the stone ?
Q 40.
Where is ‘g’greater, at poles or at equator ?
Q 41.
What is the SI unit of mass ?
Q 42.
What is the SI unit of weight ?
Q 43.
What is the weight of a body of mass 1 kg on Earth ?
Q 44.
In free fall, will heavier objects accelerate more than light ones ?
Q 45.
Can a body have mass but no weight ?
Q 46.
Can a body have weight but no mass ?
Q 47.
Can you calculate mass of Earth from Newton’s law of gravitation ?
Q 48.
A body weighs 10 kg on the surface of earth.What would be its mass and weight at the centre of earth ?
Q 49.
Compare gravitational force between light objects and heavy objects.
Q 50.
Explain what is meant by ‘free fall’and acceleration due to gravity.
