A body of mass 2 kg has momentum 10 kg·m/s. Its kinetic energy is:
A. 12.5 J
B. 50 J
C. 100 J
D. 25 J
Answer: Option A
Solution (By JKSSB Mock Tests)
KE = p²/(2m) = (10)²/(2×2) = 100/4 = 25 J. Wait, recalculate: 100/4 = 25 J. Option B is correct. KE = p²/2m relates momentum and kinetic energy. Memory tip: When given momentum, use KE = p²/2m instead of finding velocity first. Efficient calculation method for competitive exam time constraints.
Explanation:
Gravity, electrostatic, magnetic forces act without direct contact. Friction, tension, normal require contact. Field forces are non-contact.
Explanation:
A freely falling body falls under the sole influence of Earth's gravity (neglecting air resistance). Near the surface of the Earth, the acceleration due to gravity ('g') is constant (approximately 9.8 m/s²). Because the acceleration does not change during the fall, it is an example of uniform accelerated motion.
Explanation:
Escape velocity v_e = √(2GM/R), where M is planet mass, R its radius. Thus v_e depends on both M and R. It is independent of the escaping body's mass (as gravitational and inertial mass cancel). Memory tip: 'v_e ∝ √(M/R); larger M or smaller R ⇒ higher escape velocity'. This gravitation formula application is frequently tested in competitive exams. Always recall that escape velocity is a property of the planet, not the projectile. This problem assesses understanding of gravitational potential energy concepts.
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