Newton's first law defines: MCQ with Answer and Explanation

Newton's first law defines:

A. Inertia

B. Momentum

C. Acceleration

D. Force

Answer: Option A

Solution (By JKExamLibrary)

Newton's first law (law of inertia) states bodies remain at rest or uniform motion unless acted upon by external force. This defines inertia - resistance to change in motion state. Force is defined in second law; momentum conservation in third. Memory aid: 'First law = inertia; second = F=ma; third = action-reaction'. Fundamental concept frequently tested to assess basic mechanics understanding.

This question belongs to: Science Physics

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Practice More Physics Questions

Question #1 Report Error

Object floats with 40% volume submerged. Density ratio (object/liquid) is:

A. 0.4

B. 1.4

C. 0.6

D. 2.5

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Correct Answer: Option A

Explanation:
Floatation: weight = buoyant force ⇒ ρ_obj·V·g = ρ_liq·V_sub·g ⇒ ρ_obj/ρ_liq = V_sub/V = 0.4. Fraction submerged equals density ratio. Memory tip: 'Submerged fraction = ρ_object/ρ_fluid'. Direct Archimedes' principle application frequently tested in buoyancy sections of competitive exams.

This question belongs to: Science Physics

Question #2 Report Error

A 100 W bulb operates at 220 V. The current drawn by it is approximately:

A. 4.5 A

B. 0.45 A

C. 0.22 A

D. 2.2 A

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Correct Answer: Option B

Explanation:
Electric power P = VI. Thus I = P/V = 100 W / 220 V ≈ 0.4545 A ≈ 0.45 A. This direct application of power formula is fundamental in electricity. Memory tip: 'I = P/V for resistive loads'. Competitive exams frequently test such calculations with household appliance ratings. Always use consistent units (watts, volts, amperes). Note: This assumes purely resistive load (valid for incandescent bulbs); for motors or electronics, power factor may matter, but not at this level.

This question belongs to: Science Physics