Question

The time taken for a bike moving with an acceleration of 2ms to increase it's velocity from 12ms to 36 ms is
1/12s
2/15s
3/18s
4/20s​

Answer 1

initial velocity (u)= 12ms

final velocy(v)=36ms

acceleration (a)=2ms

substitute the given values in the formula

v=u+at

36=12+2×t

t=36-12÷2

=12ms

Answer 2

Answer:

Provided that:

• Acceleration = 2 m/s sq.
• Initial velocity = 12 m/s
• Final velocity = 36 m/s

To calculate:

• Time taken

Solution:

• Time taken = 12 s

Using concept(s):

• To solve this question we can use either first equation of motion or formula to calculate the acceleration!

• Choice may vary!

Using formula(s):

• Acceleration is given by,

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

• First equation of motion,

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

Required solution:

~ By using acceleration formula!

$:\implies \sf Acceleration \: = \dfrac{Change \: in \: velocity}{Time} \\ \\ :\implies \sf a \: = \dfrac{v-u}{t} \\ \\ :\implies \sf 2 \: = \dfrac{36-12}{t} \\ \\ :\implies \sf 2 \: = \dfrac{24}{t} \\ \\ :\implies \sf t \: = \dfrac{24}{2} \\ \\ :\implies \sf t \: = 12 \: s \\ \\ :\implies \sf Time \: = 12 \: seconds$

Henceforth, time = 12 seconds!

~ Now by using first equation of motion!

$:\implies \sf v \: = u \: + at \\ \\ :\implies \sf 36 = 12 + 2(t) \\ \\ :\implies \sf 36 - 12 = 2t \\ \\ :\implies \sf 24 = 2t \\ \\ :\implies \sf t \: = \dfrac{24}{2} \\ \\ :\implies \sf t \: = 12 \: s \\ \\ :\implies \sf Time \: = 12 \: seconds$

Henceforth, time = 12 seconds. Therefore, option 1st is correct!!!