JEE PHYSICS MCQ: MOTION IN A STRAIGHT LINE

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Assertion (A): Starting from rest with zero acceleration if acceleration of particle increases at a constant rate of

2 \mathrm{~ms}^{-3}

then velocity should increase at constant rate of

1 \mathrm{~ms}^{-2}

.

Reason (R): For the given condition.

\frac{d a}{d t} =2 \mathrm{~ms}^{-3}

a =2 t

View answer and explanation

Correct option: D

If Assertion is false but the Reason is true.

Option D is correct because the assertion is false, as the velocity increases at a non-constant rate, while the reason correctly derives the acceleration as a function of time.

More Questions from MOTION IN A STRAIGHT LINE

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Assertion: In a free fall, the initial velocity of a body may not be zero.
Reason: Free fall means the vertical acceleration of the body is equal to

\mathrm{g}

. A ball is thrown vertically upward with speed 15 m/s and it returns to the ground with speed 10 m/s as a constant air resistance acts. The maximum height attained by the ball is Which of the following is not a derived quantites? Assertion: If a body is dropped from the top of a tower of height

\mathrm{h}

and another body is thrown up simultaneously with velocity

\mathrm{u}

from the foot of the tower, then both of them would meet after a time

\frac{\mathrm{h}}{\mathrm{u}}

.
Reason: For a body projected upwards, the distance covered by the body in the last second of its upward journey is always

4.9 \mathrm{~m}

irrespective of velocity of projection.

(\mathrm{g}=9.8 \mathrm{~m} / \mathrm{s}^2)

A particle is having uniform acceleration. If its displacement from

t

(t+1)

second is

120 \mathrm{~m}

and change in velocity is

50 \mathrm{~m} / \mathrm{s}

. Find its displacement (in

\mathrm{m}

) in

(t+2)

second. An aeroplane flies 400m north and 300m south and then flies 1200m upwards, then net displacement is