Define/write the laws: Force Ans. The force is that physical quantity which changes or tends to change the state of rest or of uniform motion in a straight line. Newton’s universal law of gravitation Ans. According to the Newton’s universal law of ravitation, every object in the universe attracts every other object with a force, which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres. Universal constant of gravitation (G) Ans. Universal constant of gravitation is the force of attraction between two unit masses placed at unit distance apart from each other.

Define/write the laws: 

Force

Ans. The force is that physical quantity which changes or tends to change the state of rest or of uniform

motion in a straight line.

Newton’s universal law of gravitation

Ans. According to the Newton’s universal law of ravitation, everyobject in the universe attracts every other object with a force, which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres.

Universal constant of gravitation (G)

Ans. Universal constant of gravitation is the force of attraction between two unit masses placed at unit distance apart from each other.

Centre of mass

Ans. It is the point inside or outside the object at which the total mass of the object can be assumed to be concentrated..

Gravitational acceleration (g)

Ans. The gravitational force due to earth on a body results in its acceleration. This is called acceleration due to gravity.

Free fall

Ans. When a body falls towards the Earth under the influence of the Earth’s gravity alone, its motion  is called a ‘free fall’.

Mass (m)

Ans. The mass of an object is the quantity of matter contained in it. The mass is the measure of the inertia of a body.

Weight (W)

Ans. The weight of a body is defined as the force with which the Earth attracts the object.

Centripetal force

Ans. The force that acts on any object moving along a circle, directed towards the centre of the circle is 

called centripetal force.

Uniform circular motion

Ans. When an object moves in a circular path with uniform speed, its motion is uniform circular motion.

Potential energy

Ans. A body can have energy because of its shape or position or configuration. This is known as potential energy.

Escape velocity

Ans. The minimum initial velocity needed by an object projected upwards to overcome Earths gravitational force and not fall back on Earth is called escape velocity.