Which law explains the recoil of a gun when a bullet is fired?
A. Law of conservation of energy
B. Newton's third law
C. Newton's second law
D. Newton's first law
Answer: Option B
Solution (By JKSSB Mock Tests)
Recoil is due to action-reaction pair: gun exerts forward force on bullet, bullet exerts backward force on gun. Newton's third law states for every action there is equal and opposite reaction. Conservation of momentum also explains recoil, but the immediate law is third law. Gun recoil velocity is calculated using conservation of momentum derived from third law.
Explanation:
Fuse needs low melting point to melt at overload, high resistance to generate more heat (I²R). Tin-lead alloy suitable. Copper high melting point, not fuse material.
Explanation:
Radiation does not require medium; it travels via electromagnetic waves. Conduction needs medium for molecular collisions, convection needs fluid motion. Sun's heat reaches Earth by radiation through vacuum of space.
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