In a perfectly elastic collision between two bodies, which of the following physical quantities are conserved?
A. Both momentum and kinetic energy
B. Only momentum
C. Neither momentum nor kinetic energy
D. Only kinetic energy
Answer: Option A
Solution (By JKSSB Mock Tests)
In any collision (elastic or inelastic), the total linear momentum is always conserved, provided no external forces act on the system. However, a perfectly elastic collision is specifically defined as one in which there is absolutely no loss of kinetic energy. Therefore, both total linear momentum and total kinetic energy are conserved.
Torricelli's Law states that the velocity of efflux of a fluid through a sharp-edged hole at the bottom of a tank filled to a depth 'h' is identical to:
A.The velocity acquired by a freely falling body dropped from height 'h'.
Explanation:
Torricelli's Law is a direct application of Bernoulli's principle. It proves mathematically that the velocity of fluid exiting a small hole (efflux velocity v) is v = sqrt(2gh). This is exactly the same velocity a solid body would acquire if it fell freely under gravity from rest over the same vertical height 'h'.
Explanation:
Archimedes' principle: buoyant force = weight of displaced fluid. Law of floatation: floating body displaces fluid equal to its own weight. Archimedes discovered it. Pascal gave pressure law.
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