Question

10. A body starts from rest and travels
with an acceleration of 2 m/s. After t
seconds its velocity is 10 m/s. Then tis*
O
(a) 10 s
O (b) 5 S
(c) 20 S
(d) 6 S​

Answer 1

Answer:

v=u+at

10=0+2t

2t=10

t=5sec

Answer 2

Correct question:

A body starts from rest and travels with an acceleration of 2 m/s². After some seconds its velocity is 10 m/s. Then time taken = !?

Provided that:

• Initial velocity = 0 mps
• Acceleration = 2 m/s sq.
• Final velocity = 10 mps

To calculate:

• Time taken

Solution:

• Time taken = 5 sec (b)

Using concept(s):

• To solve this question we can use either first equation of motion or acceleration formula.

Using formula(s):

• Acceleration is given by:

• ${\small{\underline{\boxed{\pmb{\sf{a \: = \dfrac{v-u}{t}}}}}}}$

• First equation of motion:

• ${\small{\underline{\boxed{\pmb{\sf{v \: = u \: + at}}}}}}$

Where, a denotes acceleration, u denotes initial velocity, v denotes final velocity and t denotes time taken.

Required solution:

~ Let's solve this question, let us find out the time taken!

By using acceleration formula

$:\implies \sf a \: = \dfrac{v-u}{t} \\ \\ :\implies \sf 2 \: = \dfrac{10-0}{t} \\ \\ :\implies \sf 2 \: = \dfrac{10}{t} \\ \\ :\implies \sf t \: = \dfrac{10}{2} \\ \\ :\implies \sf t \: = 5 \: sec \\ \\ :\implies \sf Time \: taken \: = 5 \: sec$

By using first equation of motion

$:\implies \sf v \: = u \: + at \\ \\ :\implies \sf 10 = 0 + 2t \\ \\ :\implies \sf 10 = 2t \\ \\ :\implies \sf t \: = \dfrac{10}{2} \\ \\ :\implies \sf t \: = 5 \: sec \\ \\ :\implies \sf Time \: taken \: = 5 \: sec$

Time taken is 5 sec! Therefore, option (b) is absolutely correct!