A stone tied to a string is whirled in a circle. The work done by tension in string is
A. Negative
B. Variable
C. Zero
D. Positive
Answer: Option C
Solution (By JKSSB Mock Tests)
Tension is towards centre, displacement is tangential (velocity). Force perpendicular to displacement, cos90°=0, work zero. Centripetal force does no work, doesn't change speed.
Explanation:
The eye lens is a convex (converging) lens. It converges light rays to form a real and inverted image on the retina. The brain processes this signal and flips it so we perceive the world as erect. All other statements are functionally correct. The cornea does indeed do about two-thirds of the focusing.
Explanation:
Moderator (water, graphite) slows fast neutrons to thermal energies for efficient fission in U-235. Control rods absorb neutrons to regulate reaction. Memory tip: 'Moderator = neutron slower; Control rods = neutron absorber'. Reactor component function frequently tested in competitive nuclear physics questions.
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