Question:
Two electrons each of mass kg are at a distance of 10 A.Calculate the gravitational force of attraction between them. Given 1 A = m.
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.
Why do sewing needles and all pins have a sharp pointed tip?
Q 5.
Which force is responsible for tides in the ocean at night ?
Q 6.
What is the value of ‘g’ at the centre of Earth ?
Q 7.
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 8.
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 9.
What do we call the gravitational force between the Earth and an object ?
Q 10.
Can you calculate density of Earth from Newton’s law of gravitation ?
Q 11.
Fill in the blanks :
Every object in the universe ________ other bodies.
Q 12.
What do you mean by acceleration due to gravity ?
Q 13.
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 14.
State and explain universal law of gravitation given by Newton.What is the importance of this law
Q 15.
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 16.
Who measured the value of G first time, experimentally?
Q 17.
Fill in the blanks :
________ of an object is the force of gravity acting on it.
Q 18.
What is the importance of universal law of gravitation ?
Q 19.
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 20.
What happens to 'g' experienced by a body when it moves up the earth's surface?
Q 21.
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 22.
What are Plimsoll Lines?
Q 24.
What is value of ‘g’ on Earth ?
Q 25.
Is weight a scalar quantity?
Q 26.
Mass of an object is 10 kg. What is its weight on the Earth? (g = 9.8 m/s
2.)
Q 27.
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 28.
State and explain universal law of gravitation.What is its importance ?
Q 29.
Distinguish between mass and weight.
Q 30.
A car falls off a ledge and drops to the ground in 0.5 s.Let g =
(for simplifying the calculations).
(i) What is its speed on striking the ground ?
(ii) What is its average speed during 0.5 s ?
(iii) How high is the ledge from the ground ?
Q 31.
What is the SI unit of weight ?
Q 32.
Can a body have weight but no mass ?
Q 33.
Fill in the blanks :
______ stated that every planet moves around the sun in closed elliptical orbit, with the ___ at one focus.
Q 34.
Why is G called the Universal Constant?
Q 35.
Fill in the blanks :
Assuming negligible air drag, if a steel ball and a table tennis ball are dropped from a height of 100 metres, both will reach the ground at ________ time(s). (same/different)
Q 36.
A stone is released from the top of a tower of height 19.6 m.Calculate its final velocity just before touching the ground.
Q 37.
Fill in the blanks :
When objects of different masses and sizes are dropped from same height would reach the ground at ______ (same time/different times), considering negligible air resistance.
Q 38.
Who gave three laws of planetary motion ?
Q 39.
A stone falling towards Earth also attracts the Earth with the same force.Is it true ?
Q 40.
Then why Is the Earth not seen moving towards the stone ?
Q 41.
A body is just dropped from a height What is its initial velocity ?
Q 42.
Fill in the blanks :
Kepler's Law of ______ states that a line that connects a planet to the Sun sweeps out equal ______ in the plane of the planet's orbit in _____time intervals.
Q 43.
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 45.
Fill in the blanks :
The average acceleration of free fall on the surface of earth is ______ .
Q 46.
Why will a sheet of paper fall slower than one that is crumpled into a ball?
Q 47.
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 48.
Mass of an object is 10 kg. What is its weight on Earth ?
Q 49.
State the universal law of gravitation.
Q 50.
How does the force of gravitation between two objects change when the distance between them is reduced to half ?
