Conservation of Energy — Homi Bhabha Exam Physics MCQs with Solutions
Free Homi Bhabha Exam Physics Conservation of Energy MCQs with step-by-step solutions (7 questions). Part of Work, Energy & Power. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Conservation of Energy · medium · theory
The law of conservation of energy states that energy:
A. can be created but not destroyed
B. is lost during every change
C. can neither be created nor destroyed, only changed from one form to another ✓ Correct
D. can be destroyed but not created
Solution: The total energy of an isolated system stays constant; it only transforms between forms.
Q2 — Conservation of Energy · hard · theory
For a freely falling body, as it falls its potential energy decreases and its kinetic energy:
A. remains constant
B. becomes zero
C. increases by the same amount ✓ Correct
D. decreases
Solution: P.E. converts to K.E. so that their sum (total mechanical energy) stays constant.
Q3 — Conservation of Energy · hard · numerical
A stone of mass 1 kg is thrown up and reaches a height of 8 m. Its potential energy at the top (taking $g = 10$ m/s²) equals its initial kinetic energy of:
A. 8 J
B. 800 J
C. 80 J ✓ Correct
D. 40 J
Solution: At the top all K.E. becomes P.E.: initial K.E. $= mgh = 1 \times 10 \times 8 = 80$ J.
Q4 — Conservation of Energy · medium · theory
In a simple pendulum swinging back and forth, the energy continuously changes between:
A. sound and kinetic
B. heat and light
C. kinetic and potential energy ✓ Correct
D. chemical and potential
Solution: At the extremes energy is potential; at the mean position it is kinetic — the two interchange.
Q5 — Conservation of Energy · hard · theory
A body falls from a height. At the mid-point of its fall (ignoring air resistance):
A. it has only kinetic energy
B. its total energy is halved
C. it has only potential energy
D. its kinetic energy equals its potential energy ✓ Correct
Solution: At half the height, half the initial P.E. has become K.E., so K.E. = P.E. there (total energy unchanged).
Q6 — Conservation of Energy · medium · theory
When a ball is dropped and bounces to a lower height each time, the "lost" mechanical energy is mainly converted into:
A. nuclear energy
B. chemical energy
C. heat and sound ✓ Correct
D. light and electricity
Solution: Energy is not destroyed; it is dissipated as heat and sound during each bounce.
Q7 — Conservation of Energy · medium · theory
In a hydroelectric power plant, the energy of falling water is converted mainly into:
A. electrical energy ✓ Correct
B. nuclear energy
C. chemical energy
D. sound energy
Solution: The potential/kinetic energy of falling water spins turbines and generators to produce electrical energy.