Kevin Nash
Last Activity: 9 Years ago
The correct options are (A), (B) and (E).
(a) Mass is an absolute quantity. Mass of a body can be regarded as a quantitative measure of the resistance of a body to acceleration by a given force. Therefore mass of the body can never be negative.
(B) Time is not an absolute quantity. According to Einstein special theory of relativity, time can be shortening if the frame of reference is moving comparable to the speed of light. Therefore time can never be negative.
(C) As per the convention, when work is done by the system then the sign of the work done will be positive whereas work is done on the system then the sign of the work done will be negative. Therefore work can be negative or positive.
(D) Potential energy can be negative because potential energy due to gravity is also a negative quantity.
(E) Kinetic energy (K) of a body is defined as the,K = ½ mv2, where m is the mass of the body and v is the velocity of the body.
Since, mass of the body (m) is always a positive quantity and the term v2 in the kinetic energy is always positive, therefore, kinetic energy of a body is always a positive quantity. Therefore kinetic energy can never be negative.
From the above observation we conclude that, the quantity mass, time and kinetic energy can never be negative. Thus options (A), (B) and (E) are correct.