Question

A body starts from rest and travels with an acceleration of 1.5 m/s². After t seconds its velocity is 6 m/s . Then t is….? (a) 10 s (b) 5 s (c) 4 s (d) 6 s​

Answer 1

Answer:

(c) 4 s

Explanation:

Given,

A body starts from rest and travels with an acceleration of 1.5 m/s² for ‘t’ seconds and reaches a velocity of 6m/s

Find the value of ‘t’

By the first equation of motion,

$\rm \implies \: v = u + at$

Where,

• v(final velocity) = 6m/s
• u(initial velocity) = 0m/s [since it starts from rest]
• a(acceleration) = 1.5m/s²

Solving for ‘t’ :-

$\rm \implies \: v = u + at$

$\rm \implies \: 6 = 0 + (1.5)t$

$\rm \implies \: 6 = 0 + 1.5t$

$\rm \implies \: 6 = 1.5t$

$\rm \implies \: \dfrac{6}{1.5} = t$

$\rm \implies \: t = 4$

∴ The value of ‘t’ is 4 seconds

__________________________

Note:

First equation of motion,

$\rm \implies \: v = u + at$

Where,

• ‘v’ denotes the final velocity
• ‘u’ is the initial velocity
• ‘a’ is acceleration
• and ‘t’ is time taken.

Answer 2

Given :-

A body starts from rest and travels with an acceleration of 1.5 m/s². After t seconds its velocity is 6 m/s

To Find :-

Time taken

Solution :-

We know that

a = (v - u)/t

t = (v - u)/a

t = (6 - 0)/1.5

t = 6/1.5

t = 60/15

t = 4 s

Hence

Time taken is 4 s