Q (1): Assertion : Push a pebble lying on a surface and the pebble moves through a distance.
Reason : You exerted a force on the pebble and the pebble got displaced.
Q (2): Assertion : If F = 1 N and s = 1 m then the work done by the force will be 1 N m.
Reason : Work done by a force acting on an object is equal to the magnitude of the force multiplied by the distance moved in the direction of the force.
Q (3): Assertion : The work done by a force can be either positive or negative.
Reason : The work done will be equal to the product of the force and displacement.
Q (4): Assertion : Work done is negative when the force acts opposite to the direction of displacement.
Reason : Work done is positive when the force is in the direction of displacement.
Q (5): Assertion : 1 J is the energy required to do 1 joule of work.
Reason : The energy possessed by an object is thus measured in terms of its capacity of doing work.
Q (6): Assertion : A falling coconut, a speeding car, a rolling stone, a flying aircraft, flowing water, blowing wind, a running athlete etc. possess kinetic energy.
Reason : Objects in motion possess kinetic energy.
Q (7): Assertion : Kinetic energy is the energy possessed by an object due to its motion.
Reason : The kinetic energy of an object decreases with its speed.
Q (8): Assertion : The kinetic energy possessed by an object of mass, m and moving with a uniform velocity, v is KE = 1/2 mv2.
Reason : The kinetic energy of an object increases with its speed.
Q (9): Assertion : An object of mass 15 kg is moving with a uniform velocity of 4 ms-1and kinetic energy of that object will be 120 J.
Reason : The kinetic energy possessed by an object of mass, m and moving with a uniform velocity, v is KE = 1/2 mv2.
Q (10): Assertion : The energy transferred to an object is stored as potential energy if it is not used to cause a change in the velocity or speed of the object.
Reason : The potential energy possessed by the object is not the energy present in it by virtue of its position or configuration.
Q (11): Assertion : An object increases its energy when raised through a height.
Reason : This is because work is done on it against gravity while it is being raised.
Q (12): Assertion : The energy possessed by an object of mass 10 kg when it is at a height of 6 m above the ground is 588 J.
Reason : Since work done on a object at height is equal to mgh, an energy equal to mgh units is gained by the object.
Q (13): Assertion : The work done by gravity depends on the difference in vertical heights of the initial and final positions of the object and not on the path along which the object is moved.
Q (14): Assertion : Whenever energy gets transformed, the total energy remains unchanged.
Reason : Energy can not be converted from one form to another.
Q (15): Assertion : The total energy before and after the transformation remains the same
.Reason : Energy can only be converted from one form to another; it can neither be created or destroyed.
