Question:
What is the acceleration of free fall ?
Answer:
All objects moving towards Earth on account of gravitational force of Earth on them are said to be in free fall.This force produces a uniform acceleration in the objects.This is the acceleration of free fall,and is called acceleration due to gravity.
Gravitation
Q 1.
Is mass a scalar quantity?
Q 2.
Explain what is meant by ‘free fall’and acceleration due to gravity.
Q 3.
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 4.
What are the factors the buoyant force depends on?
Q 5.
What is the SI unit of weight ?
Q 6.
How are gravitation and gravity related ?
Q 7.
Can you calculate mass of Earth from Newton’s law of gravitation ?
Q 8.
Comment on application of Newton’s third law of motion to gravitation.Illustrate by examples.
Q 9.
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 10.
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 11.
A stone falling towards Earth also attracts the Earth with the same force.Is it true ?
Q 12.
Distinguish between mass and weight.
Q 13.
Two particles of equal mass (m) move in a circle of radius (r) under the action of their mutual gravitational attraction. Find the speed of each particle.
Q 14.
Who measured the value of G first time, experimentally?
Q 15.
What are the differences between the mass of an object and its weight?
Q 17.
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 18.
Fill in the blanks :
It is the ____________ of the earth, which holds our atmosphere in place.
Q 19.
The pressure at the bottom of a filled glass (density = 1000 kg/m
3) of water is P. The water is taken out and the glass is filled with kerosene oil (density = 817.5 kg/m
3). Now the pressure at the bottom will be a. same as P b. smaller than P c. larger than P d. cannot be determined.
Q 20.
If the distance of Earth from the Sun were half the present value,how many days will make one year ?
Q 21.
Who gave three laws of planetary motion ?
Q 22.
Does value of ‘g’ vary from place to place on Earth ?
Q 23.
What is the value of ‘g’ at the centre of Earth ?
Q 24.
State Kepler’s Laws of planetary motion.
Q 25.
On earth,value of G =
.What is its value on moon,where g is nearly
th that of earth ?
Q 26.
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 28.
Why is the weight of an object on the moon 1/6th its weight on the earth?
Q 29.
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 30.
Why do sewing needles and all pins have a sharp pointed tip?
Q 31.
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 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.
How does the force of gravitation between two objects change when the distance between them is reduced to half ?
Q 34.
What is the value of G (i) on Earth (ii) on Moon ?
Q 35.
Which force revolves Moon around Earth ?
Q 36.
Which force accelerates a body in free fall ?
Q 37.
What is the usual shape of orbits of planets around the Sun ?
Q 38.
Does Newton’s third law of motion apply to gravitational force ?
Q 39.
Can you calculate density of Earth from Newton’s law of gravitation ?
Q 40.
Compare gravitational force between light objects and heavy objects.
Q 41.
In Fig.,the line that joins a planet to the sun sweeps out areas
,
in time intervals 6 weeks,3 weeks and 2 weeks respectively.How are
,
realted ?
Q 42.
Fill in the blanks :
Heliocentric model was proposed by ______.
Q 43.
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 44.
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 45.
Fill in the blanks :
Acceleration due to gravity (g) is _______ (dependent/independent) of mass.
Q 46.
Fill in the blanks :
The value of
g on the earth's surface is ______.
Q 47.
Fill in the blanks :
The value of
g at poles is ______ (lower/higher) than its value at the equator.
Q 48.
Why is G called the Universal Constant?
Q 49.
How does value of 'g' vary on the earth? What are the factors responsible for this?
Q 50.
What happens to 'g' experienced by a body when it moves up the earth's surface?
