Question

A body starting from rest is moving with a uniform acceleration of 8 metre per second square. Then the distance travelled by it in the fifth second will be?

Answer 1

Body started from rest, u =0 m/s

acceleration = 8m/s²

We know that displacement in the nth second = u+ a ( n -1/2)

Displacement in 5th second

=0+(5-1/2)*8

=9/2*8

=36m

the distance travelled by it in the fifth second will be 36 m

Answer 2

Heya user !!!

Here's the answer you are looking for

Since, the body starts from rest, it's initial velocity (u) = 0

And acceleration (a) = 8m/s²

Distance travelled by it in 5th second can be found in 2 ways

One is directly using the formula

S(nth) = u + a(n - 1/2)

S(5th) = 0 + (8)(5 - 1/2) = 8(9/2) = 36m

Other way is find the distance travelled in nsec, find the distance travelled in (n-1)sec then subtract it.

Here,
S(5) - S(4) = {0 + 8 × 5²/2 } - {0 + 8 × 4²/2}

= 4 × 5² - 4 × 4²

= 4 (5² - 4²)

= 4 ( 25 - 16)

= 4 (9)

= 36m


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