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JEE PHYSICS MCQ: MOTION IN A STRAIGHT LINE

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If a particle is moving along a straight line and its velocity varies with time, as

v=2 t-t^2

, (

v

and

t

are in

\mathrm{SI}

units) then choose the incorrect option.

View answer and explanation

Correct option: D

Average speed from

t=0

to

t=2 \mathrm{~s}

is

\frac{5}{12} \mathrm{~m} / \mathrm{s}

Option D is correct because the average speed from t=0 to t=2 s is calculated as 2/3 m/s, not 5/12 m/s, due to the particle changing direction.

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)

120 \mathrm{~m}

and change in velocity is

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

. Find its displacement (in

\mathrm{m}

(t+2)

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