The kinetic energy of a body is increased by 300%. The percentage increase in its momentum is: MCQ with Answer and Explanation

The kinetic energy of a body is increased by 300%. The percentage increase in its momentum is:
A. 100%
B. 400%
C. 200%
D. 300%
Answer: Option A
Solution (By JKSSB Mock Tests)
KE ∝ p² (since KE = p²/(2m)). If KE increases by 300%, new KE = 4× original KE. Thus p_new² / p_original² = 4 ⇒ p_new / p_original = 2 ⇒ momentum doubles, i.e., 100% increase. Memory tip: 'KE ∝ p²; so %Δp = ½ %ΔKE for small changes, but for large changes use ratio'. This proportional reasoning problem tests energy-momentum relationship, frequently appearing in competitive exams. Always derive from fundamental relations when percentages are large; linear approximations fail here.

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Practice More Physics Questions

Question #1
A piece of ice is floating in a glass of water. When ice melts, water level
A. Rises
B. First falls then rises
C. Remains same
D. Falls

Correct Answer: Option C


Explanation:
Ice displaces water equal to its weight; when melted, occupies exactly that volume. Level unchanged.

This question belongs to: Science Physics
Question #2
The time period of revolution of a satellite close to Earth's surface is approximately:
A. 24 hours
B. 12 hours
C. 90 minutes
D. 84 minutes

Correct Answer: Option D


Explanation:
For low Earth orbit (r ≈ R_earth), orbital period T = 2π√(r³/GM). Using g = GM/R², T = 2π√(R/g). With R = 6.4×10⁶ m, g = 9.8 m/s², T ≈ 2×3.14×√(6.4e6/9.8) ≈ 6.28×√(653061) ≈ 6.28×808 ≈ 5076 s ≈ 84.6 minutes. Memory aid: 'Low orbit period ≈ 84 min; geostationary = 24 hours'. This standard result is frequently tested in competitive exams. Always recall that period increases with orbital radius; competitive exams often compare low orbit vs geostationary periods.

This question belongs to: Science Physics
Question #3
According to the Universal Law of Gravitation, the force of attraction between two bodies is inversely proportional to:
A. The square of the distance between their centers.
B. The product of their masses.
C. The sum of their masses.
D. The distance between them.

Correct Answer: Option A


Explanation:
Newton's Law of Universal Gravitation states that the gravitational force (F) between two point masses is directly proportional to the product of their masses (m1 × m2) and inversely proportional to the square of the distance (r²) between their centers. The mathematical formula is F = G(m1m2)/r².

This question belongs to: Science Physics