Question:
A cuboid room has dimensions 50m x 15m x 3.5m. What is the mass of the air enclosed in the room if the density of air = 1.30 kg/m3.
Answer:
Volume of room (V) = 50m x 15m x 3.5m = 2625m3
Density of air (d) = 1.30 kg/m3
Mass of air = V x d = 2625 x 1.30 = 3412.5 kg
Gravitation
Q 1.
State Kepler’s Laws of planetary motion. How did Newton guess inverse square law ?
Q 2.
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 3.
Can you calculate density of Earth from Newton’s law of gravitation ?
Q 4.
What do we call the gravitational force between the Earth and an object ?
Q 5.
What is the value of ‘g’ at the centre of Earth ?
Q 6.
What do you mean by acceleration due to gravity ?
Q 7.
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 8.
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 9.
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 10.
Fill in the blanks :
Weight of an object is the product of ______ and ________.
Q 11.
Why do sewing needles and all pins have a sharp pointed tip?
Q 12.
Fill in the blanks :
Every object in the universe ________ other bodies.
Q 13.
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 14.
Calculate the value of acceleration due to gravity on Moon. Given mass of Moon =
kg, radius of Moon = 1740 km
Q 15.
What are the Kepler Laws that govern the motion of the planets?
Q 16.
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 18.
Is weight a scalar quantity?
Q 19.
In what direction does the buoyant force on an object immersed in a liquid act?
Q 20.
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 21.
Can a body have weight but no mass ?
Q 22.
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 23.
Fill in the blanks :
The value of
g on the earth's surface is ______.
Q 24.
Write the standard equations of motion when an object is thrown upwards with some initial velocity?
Q 25.
Name the scientist who identified the relation about force of gravitation. Name the law.
Q 26.
Is mass a scalar quantity?
Q 27.
Fill in the blanks :
The gravitational force between the earth and the object is generally called ____________.
Q 28.
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 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.
A solid block of density 6000 kg/m
3 weighs 0.6 kg in air. It is completely immersed in water of density 1000 kg/m
3. Calculate the apparent weight of the block in water and the buoyant force. (Take g = 10ms
-2)
Q 31.
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 32.
The distance between two objects is doubled. What happens to gravitational force between them
Q 33.
Where is ‘g' maximum, on the surface of Earth, above the surface or below the surface of Earth ?
Q 34.
Can a body have mass but no weight ?
Q 35.
Compare gravitational force between light objects and heavy objects.
Q 36.
Fill in the blanks :
Geocentric model i.e. the Earth is the orbital centre of all celestial bodies was proposed by _____.
Q 37.
Fill in the blanks :
According to the Heliocentric theory, the _____ is at centre and _______ move around it.
Q 38.
Fill in the blanks :
The value of Universal Gravitation constant (G) is ________ Nm
2kgs
-2.
Q 39.
Fill in the blanks :
The value of
g ________ (increases/decreases) as we go upwards from the earth's surface.
Q 40.
Why is G called the Universal Constant?
Q 41.
Who measured the value of G first time, experimentally?
Q 42.
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 43.
An object is placed at the surface of the earth and is at distance R from the center of the earth. The object weighs 180N. What will be its weight if it is at distance 3R from the center of the earth.
Q 44.
What happens to 'g' experienced by a body when it moves up the earth's surface?
Q 45.
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 47.
Define weight? How it is related to mass?
Q 48.
Mass of an object is 10 kg. What is its weight on the Earth? (g = 9.8 m/s
2.)
Q 49.
Is acceleration due to gravity a vector or a scalar? Write its S.I. unit.
Q 50.
The tangential velocity of a planet or moon moving in a circle is at a right angle to ____________. (fill in the blank)
