Question:
What are the Kepler Laws that govern the motion of the planets?
Answer:
Kepler three laws are:
- THE LAW OF ORBITS: All planets move in elliptical orbits. with the Sun at one focus.
- THE LAW OF AREAS: A line that connects a planet to the Sun sweeps out equal areas in the plane of the planet's orbit in equal time intervals. It implies that the planet will move most slowly when it is farthest from the Sun and most rapidly when it is nearest to the Sun.
- THE LAW OF PERIODS: The square of the orbital period (T) of any planet is proportional to the cube is of its orbit (r) i.e. T2 ∝ r3
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.
What do we call the gravitational force between the Earth and an object ?
Q 4.
Is weight a scalar quantity?
Q 5.
Can you calculate density of Earth from Newton’s law of gravitation ?
Q 6.
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 7.
What is the value of ‘g’ at the centre of Earth ?
Q 8.
Why do sewing needles and all pins have a sharp pointed tip?
Q 9.
What do you mean by acceleration due to gravity ?
Q 10.
Fill in the blanks :
Weight of an object is the product of ______ and ________.
Q 11.
The distance between two objects is doubled. What happens to gravitational force between them
Q 12.
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 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.
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 16.
What is the gravitational force between the Earth and a body called? In which direction does it occur?
Q 17.
Fill in the blanks :
Every object in the universe ________ other bodies.
Q 18.
You find your mass to be 42 kg on a weighing machine. Is your mass more or less than 42 kg?
Q 19.
What is the gravitational acceleration of a spaceship at a distance equal to two Earth’s radius from the centre of the Earth ?
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.
What is the acceleration of free fall ?
Q 22.
Can a body have weight but no mass ?
Q 23.
Fill in the blanks :
Geocentric model i.e. the Earth is the orbital centre of all celestial bodies was proposed by _____.
Q 24.
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 25.
(a) What is the relationship between g and G?
(b) Show mathematically whether g (acceleration due to gravity on the earth) depends on the mass of the object itself or not.
(c) Show that for a given location on the surface of the earth g is almost constant.
Q 26.
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 27.
Write the standard equations of motion when an object is thrown upwards with some initial velocity?
Q 28.
Name the scientist who identified the relation about force of gravitation. Name the law.
Q 29.
Fill in the blanks :
A body is said to be in _______ when only gravity acts on it.
Q 30.
Fill in the blanks :
The gravitational force between the earth and the object is generally called ____________.
Q 31.
Why is it difficult to hold a school bag having a strap made of a thin and strong string?
Q 32.
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 33.
What do you mean by free fall ?
Q 34.
Which force accelerates a body in free fall ?
Q 35.
Then why Is the Earth not seen moving towards the stone ?
Q 36.
What is the weight of a body of mass 1 kg on Earth ?
Q 37.
Can a body have mass but no weight ?
Q 38.
State Kepler’s Laws of planetary motion.
Q 39.
Fill in the blanks :
The force of attraction between two objects is ______ proportional to the product of their masses and _____ proportional to the square of a distance between them.
Q 40.
Fill in the blanks :
The value of
g on the earth's surface is ______.
Q 41.
What are the Kepler Laws that govern the motion of the planets?
Q 42.
Why is G called the Universal Constant?
Q 43.
Who measured the value of G first time, experimentally?
Q 44.
Does Law of gravitation obey Newton's third law of motion?
Q 45.
What happens to 'g' experienced by a body when it moves up the earth's surface?
Q 46.
Define weight? How it is related to mass?
Q 47.
Mass of an object is 10 kg. What is its weight on the Earth? (g = 9.8 m/s
2.)
Q 48.
A stone is thrown vertically upward with an initial velocity of 40 m/s. Taking g = 10 m/s
2, find the maximum height reached by the stone. What is the net displacement and the total distance covered by the stone?
Q 50.
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.