Q (1): Assertion: Mass of an object is always zero.

  Reason: Mass of an object is the measure of its inertia and the substance contained by the body.

  Q (2): Assertion: On moon, man feels lighter than earth.

  Reason: Due to more gravitational force exerted by moon on man.

Q (3): Assertion: If the distance between two bodies of mass m1 , and  m2, is increased by a factor of 5, the gravitational force is reduced by   1/25

Reason: The gravitational force is inversely proportional to the square of the distance between two bodies

Q (4): Assertion: An object thrown vertically upward with certain velocity v, reaches maximum height and fall back with same velocity.

 Reason: Whenever an object falls towards the earth, gravitational force of the earth causes acceleration

  Q (5): Assertion : During a journey from the earth to the moon and back, maximum fuel is spent to overcome the earth’s gravity at take off.

Reason : Earth’s mass is much greater than that of the moon.

  Q (6): Assertion (A): When distance between two bodies is doubled and also mass of each body is doubled, gravitiational force between them becomes half.

Reason (R): According to Newton's law of gravitation, force is directly proportional to masses of the bodies and inversely proportional to square of distance between them.

  Q (7): Assertion (A): Earth is  attracted towards the object but with a very small acceleration.

 Reason (R): According to Newton's law of motion, if Earth attracts an object towards itself, then the object should also attract the Earth.

  Q (8): Assertion (A): The direction of acceleration is always towards the Earth.

  Reason (R): The value of "g" is 9.8m/s2 .

  Q (9): Assertion (A): The value of "g" is greater at the poles than at the equator.

  Reason (R): Radius is more at the equator than at the poles.

  Q (10): Assertion (A): An object experiences acceleration during free fall.

 Reason (R): Acceleration experienced by an object during free fall is independent of its mass.

  Q (11): Assertion (A): The S.I unit of weight is the same as that of force, that is, newton.

 Reason (R): As the weight of an object is the force with which it is attracted towards the earth.

  Q (12): Assertion (A): At the centre of Earth, a body has a centre of gravity but no centre of mass.

 Reason (R): Acceleration due to gravity at the centre of the Earh is zero.

  Q (13): Assertion (A) : If we drop a stone and a sheet of paper from a balcony of first floor, then stone will reach the ground first.

Reason (R) :The air resistance depends on velocity only.

  Q (14): Assertion (A): The value of g is different at different places.

  Reason (R): g depends on your distance from the centre of the Earth.

  Q (15): Assertion (A): The value of G is same everywhere.

Reason (R): G is universal constant equal to  6.67x10-11   Nm2/kg2.

  Q (16): Assertion (A): The mass of body is same on Moon and Earth.

  Reason (R): The mass of body is measure of inertia and is same everywhere.

  Q (17): Assertion : A block of ice with a lead shot embeddedin it floats on water contained in a vessels. Thetemperature of the system is kept at 00C as the icemelts. When ice has melted completely, water level inthe vessel rises.

Reason : The melted ice will raise the water level.

  Q (18): Assertion : Universal gravitational constant G is a scalar quantity.

 Reason : The value of G is independent of direction and is a constant through out the universe.

  Q (19): Assertion : The value of acceleration due to gravity changes with the height, depth and shape of the earth.

  Reason : Acceleration due to gravity is zero at the centre of the earth.