Question:
What are the differences between the mass of an object and its weight?
Answer:
| Mass | Weight |
|---|
| 1. It is the quantity of the matter contained in the body. | 1. It is the gravitational force of attraction on the body by the earth(planet). |
| 2. SI unit is kg | 2. SI unit is Newton(N) |
| 3. It is a scalar quantity i.e. has magnitude only. | 3. It is a vector quantity i.e. has both magnitude and direction. e.g. On the Earth, its direction is always towards the centre of the earth/planet. |
| 4. It is a measure of inertia of the body. | 4. It is the measure of the gravity. |
| 5. It is measured by physical or beam balance. | 5. It is measured by spring balance calibrated to read in Newton scale or Kg-Wt. |
| 6. It is constant for a body and does not change from place to place. | 6. It is not constant but varies as the value of gravity changes place to place. |
Gravitation
Q 1.
State Kepler’s Laws of planetary motion. How did Newton guess inverse square law ?
Q 2.
Why do sewing needles and all pins have a sharp pointed tip?
Q 3.
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 4.
Calculate the value of acceleration due to gravity on Moon. Given mass of Moon =
kg, radius of Moon = 1740 km
Q 5.
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 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.
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 8.
Fill in the blanks :
Every object in the universe ________ other bodies.
Q 9.
What is the value of ‘g’ at the centre of Earth ?
Q 10.
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 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.
What do you mean by acceleration due to gravity ?
Q 13.
What do we call the gravitational force between the Earth and an object ?
Q 14.
Which force is responsible for tides in the ocean at night ?
Q 15.
State and explain universal law of gravitation given by Newton.What is the importance of this law
Q 16.
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 17.
Can you calculate density of Earth from Newton’s law of gravitation ?
Q 18.
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 19.
Fill in the blanks :
The value of
g at poles is ______ (lower/higher) than its value at the equator.
Q 20.
Fill in the blanks :
________ of an object is the force of gravity acting on it.
Q 21.
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 22.
Fill in the blanks :
Heliocentric model was proposed by ______.
Q 23.
Who measured the value of G first time, experimentally?
Q 25.
What is the gravitational acceleration of a spaceship at a distance equal to two Earth’s radius from the centre of the Earth ?
Q 26.
What is the importance of universal law of gravitation ?
Q 27.
The distance between two objects is doubled. What happens to gravitational force between them
Q 28.
What happens to 'g' experienced by a body when it moves up the earth's surface?
Q 29.
Write the standard equations of motion when an object is thrown upwards with some initial velocity?
Q 30.
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 31.
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 32.
State and explain universal law of gravitation.What is its importance ?
Q 33.
Fill in the blanks :
The value of
g on the earth's surface is ______.
Q 34.
The tangential velocity of a planet or moon moving in a circle is at a right angle to ____________. (fill in the blank)
Q 35.
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 36.
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/m
3.
Q 37.
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 38.
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 39.
What is value of ‘g’ on Earth ?
Q 40.
What is the SI unit of mass ?
Q 41.
A body weighs 10 kg on the surface of earth.What would be its mass and weight at the centre of earth ?
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.
Fill in the blanks :
Weight of an object is the product of ______ and ________.
Q 44.
What are the Kepler Laws that govern the motion of the planets?
Q 45.
Why is G called the Universal Constant?
Q 46.
Amit buys few grams of gold at the poles as per the instruction of one of his friends. He hands over the same when he meets him at the equator. Will the friend agree with the weight of gold bought? If not, why? [Hint: The value of g is greater at the poles than at the equator].
Q 47.
A ball is thrown up and is caught by the player after 4 seconds.How high did it go and with what velocity was it thrown? How far below the ball will be from its highest point after 3 seconds from start?
Q 48.
When a ball is thrown upwards, it falls back to the ground. Name the force which makes it fall.
Q 50.
Fill in the blanks :
The gravitational force between the earth and the object is generally called ____________.
