A ball is dropped from a height of 20 m. Time to reach ground (g=10) is MCQ with Answer and Explanation

A ball is dropped from a height of 20 m. Time to reach ground (g=10) is
A. 4 s
B. 1 s
C. 2 s
D. 3 s
Answer: Option C
Solution (By JKSSB Mock Tests)
h = ½gt² => t = √(2h/g) = √(40/10) = √4 = 2 s. Free fall formula. Final velocity v = gt = 20 m/s.

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Practice More Physics Questions

Question #1
Two waves of identical frequency and amplitude superimpose in the same medium. If they meet perfectly in phase (crest meets crest), the resulting amplitude is:
A. Four times the individual amplitude
B. Same as the individual amplitude
C. Zero
D. Twice the individual amplitude

Correct Answer: Option D


Explanation:
This is an example of constructive interference. According to the principle of superposition, the resultant displacement is the algebraic sum of individual displacements. If the waves are perfectly in phase, their amplitudes add directly (A + A = 2A). Note that while amplitude doubles, the intensity (which is proportional to amplitude squared) becomes four times greater.

This question belongs to: Science Physics
Question #2
An electric iron draws 5 A at 220 V. Its power is
A. 1100 W
B. 2200 W
C. 550 W
D. 44 W

Correct Answer: Option A


Explanation:
P = V×I = 220 × 5 = 1100 W = 1.1 kW. Energy consumed in 2 hours = 2.2 kWh. Simple.

This question belongs to: Science Physics
Question #3
A lens has power +1 D. Its focal length in cm is
A. 100 cm
B. 10 cm
C. 1 cm
D. 0.1 cm

Correct Answer: Option A


Explanation:
f = 1/P = 1 m = 100 cm.

This question belongs to: Science Physics