Question:
Fill in the blanks :
The value of g at poles is ______ (lower/higher) than its value at the equator.
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.
What is the importance of universal law of gravitation ?
Q 17.
Who measured the value of G first time, experimentally?
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.
Write the standard equations in the form when an object is dropped from a height?
Q 30.
What are Plimsoll Lines?
Q 31.
Why does a block of plastic released under water come up to the surface of the water?
Q 32.
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 33.
State the universal law of gravitation.
Q 34.
What do you mean by free fall ?
Q 35.
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 36.
What is the value of G (i) on Earth (ii) on Moon ?
Q 37.
Then why Is the Earth not seen moving towards the stone ?
Q 38.
What is the SI unit of mass ?
Q 39.
What is the SI unit of weight ?
Q 40.
Can a body have mass but no weight ?
Q 41.
Can a body have weight but no mass ?
Q 42.
On earth,value of G =
.What is its value on moon,where g is nearly
th that of earth ?
Q 43.
A physics teacher explains to his students in class,the subject of motion under gravity.When a body is projected upwards from the ground with a certain velocity a,the velocity goes on decreasing at a constant rate due to gravitational pull of earth.At a certain height,this velocity becomes zero.The body cannot rise further.From this maximum height,the body begins to fall and its velocity goes on increasing at the same constant rate due to gravitational pull of earth.The body would strike the ground with exactly the same velocity (v = u),with which it was thrown initially. This is on the assumption that resistance due to air is zero, either way.
Read the above passage and answer the following questions:
(i) Why is velocity of body on striking the ground the same as initial velocity of projection of the body ?
(ii) Does the body take same time to fail to ground as the time it takes to reach the maximum height ?
(iii) What values of life do you learn from this brief study ?
Q 44.
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 45.
Fill in the blanks :
The value of
g ________ (increases/decreases) as we go downwards from the earth's surface.
Q 46.
Fill in the blanks :
The value of G was found out by _______ by using a ________.
Q 47.
What is the importance of Universal Law of Gravitation?
OR
Q: State any one phenomena related to the Universal Law of Gravitation.
Q 48.
Why is G called the Universal Constant?
Q 49.
What is the gravitational force between the Earth and a body called? In which direction does it occur?
Q 50.
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?
