Physics
Assertion (A): Mechanical energy of a freely falling body increases as it falls.
Reason (R): Potential energy is converted into kinetic energy during free fall.
- Both A and R are true and R is the correct explanation of A
- Both A and R are true and R is not the correct explanation of A
- A is true but R is false
- A is false but R is true
Answer
A is false but R is true
Explanation
Assertion (A) is false because in the case of a freely falling body (neglecting air resistance), the total mechanical energy remains constant. As the body falls, its potential energy decreases while its kinetic energy increases by an equal amount, so there is no increase in total mechanical energy.
Reason (R) is true because during free fall, the body loses potential energy and gains kinetic energy; that is, potential energy is converted into kinetic energy.
Therefore, assertion is false but reason is true.
Related Questions
According to law of conservation of energy, energy changes from one form to another form, but the total energy of that system
- increases
- decreases
- alternates
- remains the same
Water is lifted from ground floor to overhead tank at the second floor. The work done is stored in the form of :
- kinetic energy
- chemical energy
- potential energy
- both kinetic energy and chemical energy
Assertion (A): A stretched bow has kinetic energy.
Reason (R): Stretching stores potential energy.
- Both A and R are true and R is the correct explanation of A
- Both A and R are true and R is not the correct explanation of A
- A is true but R is false
- A is false but R is true
Fill in the blanks:
(a) An electric fan converts electrical energy into …………… energy.
(b) Cooking gas converts …………… energy into heat energy.
(c) Energy possessed by a compressed spring is …………… energy.
(d) The ability to do work is called …………… .
(e) The energy possessed by a body due to its position is called …………… energy.
(f) The energy possessed by a body due to its motion is called …………… energy.
(g) Green plants convert …………… energy into chemical energy.
(h) The S.I. unit of energy is …………… .
(i) An object falling freely from the roof of a multistorey building has …………… and …………… energy when halfway down the building.