Question

an object starts moving from rest with uniform acceleration and travels 20m in first 2s what will be the velocity after 10s from the start and displacement of particle in10th second
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Physics

Motion in a Straight Line

Problems on Equation of Motion

An object starting from res...

PHYSICS

An object starting from rest travels 20 m in first 2 s and 160 m in next 4 s. What will be the velocity after 7 s from the start?

December 20, 2019

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Bhavani Waswani

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ANSWER

Displacement in first 2 s, s

1

=20 m

Displacement in first 6 s, s

2

=20+160=180 m

Note that

s

1

=5×2

2

s

2

=5×6

2

It can be concluded that s=5 t

2

.......(i)

s∝t

2

⟹Acceleration is constant

From second equation of motion for uniformly accelerated motion,

s=ut+(1/2)at

2

..........(ii)

From (i) and (ii),

a/2=5

a=10 m/s

2

At the end of 7 s,

v=u+at

=0+10×7

=70 m/s