Question

A bicycle decreases its speed from 20km/h to 15km/h in 5sec find the acceleration of bicycle

​

Answer 1

Given:

Initial velocity of bicycle,u= 20 km/h

Final velocity of bicycle,v= 15 km/h

Time taken by bicycle,t= 5 s

To Find:

Acceleration of the bicycle

Solution:

We know that,

• According to first equation of motion for constant acceleration,

$\purple{\underline{\boxed{\bf{v=u+at}}}}$

where,

v is final velocity

u is initial velocity

a is acceleration

t is time taken

━━━━━━━━━━━━━━━━━━━━━━━━━

It is given that,

$\longrightarrow\rm{u=20\ km/h=20\times\dfrac{5}{18}\ m/s=\dfrac{100}{18} \ m/s}$

$\longrightarrow\rm{v=15\ km/h=15\times\dfrac{5}{18}\ m/s=\dfrac{75}{18} \ m/s}$

━━━━━━━━━━━━━━━━━━━━━━━━━

Let the acceleration of bicycle be 'a'

So, on applying first equation of motion on bicycle, we get

$\longrightarrow\rm{v=u+at}$

$\longrightarrow\rm{\dfrac{75}{18} =\dfrac{100}{18} +a(5)}$

$\longrightarrow\rm{\dfrac{75}{18}-\dfrac{100}{18}=5a}$

$\longrightarrow\rm{\dfrac{75-100}{18}=5a}$

$\longrightarrow\rm{\dfrac{-25}{18}=5a}$

$\longrightarrow\rm{5a=\dfrac{-25}{18}}$

$\longrightarrow\rm{a=\dfrac{-5}{18}}$

$\longrightarrow\rm\green{a=-0.28\ m/s^{2}}$

Hence, the acceleration of bicycle is -0.28 m/s².