Question:
The pressure at the bottom of a filled glass (density = 1000 kg/m3) of water is P. The water is taken out and the glass is filled with kerosene oil (density = 817.5 kg/m3). Now the pressure at the bottom will be a. same as P b. smaller than P c. larger than P d. cannot be determined.
Answer:
Correct answer is b. The Pressure at any point is = hdg. For the given situation h and g are fixed. So fluid with less density will apply less pressure.
Gravitation
Q 1.
Can you calculate density of Earth from Newton’s law of gravitation ?
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.
State Kepler’s Laws of planetary motion. How did Newton guess inverse square law ?
Q 4.
What do we call the gravitational force between the Earth and an object ?
Q 5.
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 6.
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 7.
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 8.
What do you mean by acceleration due to gravity ?
Q 9.
What is the value of ‘g’ at the centre of Earth ?
Q 10.
Fill in the blanks :
Every object in the universe ________ other bodies.
Q 11.
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 12.
Fill in the blanks :
________ of an object is the force of gravity acting on it.
Q 13.
Why do sewing needles and all pins have a sharp pointed tip?
Q 14.
Calculate the value of acceleration due to gravity on Moon. Given mass of Moon =
kg, radius of Moon = 1740 km
Q 15.
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 16.
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 17.
What is the gravitational acceleration of a spaceship at a distance equal to two Earth’s radius from the centre of the Earth ?
Q 18.
Fill in the blanks :
Weight of an object is the product of ______ and ________.
Q 19.
Write the standard equations of motion when an object is thrown upwards with some initial velocity?
Q 20.
Is weight a scalar quantity?
Q 21.
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 22.
What is inverse square rule ?
Q 23.
Can a body have weight but no mass ?
Q 24.
Fill in the blanks :
The gravitational force between the earth and the object is generally called ____________.
Q 25.
A force of 200 N acts on a surface of area 10 cm
2. Calculate thrust and pressure. How much the pressure changes if the area of contact increases to 50 cm
2.
Q 26.
Which force is responsible for tides in the ocean at night ?
Q 27.
Does Newton’s third law of motion apply to gravitational force ?
Q 28.
Explain what is meant by ‘free fall’and acceleration due to gravity.
Q 29.
Fill in the blanks :
The value of Universal Gravitation constant (G) is ________ Nm
2kgs
-2.
Q 30.
Fill in the blanks :
The value of
g ________ (increases/decreases) as we go upwards from the earth's surface.
Q 31.
How is gravitational force of attraction between two bodies affected if(i) Mass of both bodies is doubled.(ii) Distance between them is halved.
Q 32.
Define weight? How it is related to mass?
Q 33.
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 34.
The weight of a man is 690N which contains 5.3 x 10
-3 m
3 of blood. Find (a) blood's weight. Take density of blood is 1060 kg/m
3 (b) express it as a percentage of body weight.
Q 35.
The weight of an empty glass is 1 N. When completely filled with water, the glass weighs 4 N. If you now throw the water away and fill the glass partly with sand, the weight becomes 4 N. If the rest of the glass is now filled up with water, the weight becomes 6 N. What is the relative density of sand?
Q 36.
The distance of planet Jupiter from the sun is 5-2 times that of Earth.Find the period of revolution of Jupiter around sun.
Q 37.
Mass of an object is 10 kg. What is its weight on Earth ?
Q 38.
A ball is thrown up with a speed of 15 m/s.How high will it go before it begins to fall ? Take g=
Q 39.
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 40.
The Earth and the Moon are attracted to each other by gravitational force. Does the Earth attract the Moon with a force that is greater or smaller or the same as the force with which the Moon attracts the Earth ? Why ?
Q 41.
Fill in the blanks :
Acceleration due to gravity (g) is _______ (dependent/independent) of mass.
Q 42.
Fill in the blanks :
The value of
g at poles is ______ (lower/higher) than its value at the equator.
Q 43.
What are the Kepler Laws that govern the motion of the planets?
Q 44.
Who measured the value of G first time, experimentally?
Q 45.
What is the gravitational force between the Earth and a body called? In which direction does it occur?
Q 46.
How gravitational force is different from or similar to magnetic force (between two magnets) or coulomb force (between two charged object)?
Q 47.
Define 'g' or acceleration due to gravity? Does it depend on the mass of the body (near the surface of the earth)experiencing 'g'?
Q 48.
How does value of 'g' vary on the earth? What are the factors responsible for this?
Q 50.
Mass of an object is 10 kg. What is its weight on the Earth? (g = 9.8 m/s
2.)
