Question

The Driver Of A Three Wheeler Moving With A Speed Of 36 Km/H Sees A Child Standing In The Middle Of The Road And Brings His Vehicle To Rest In 4.0 S Just In Time To Save The Child. What Is The Magnitude Of Average Retarding Force On The Vehicle? The Mass Of Three Wheeler Is 400 Kg And Mass Of The Driver Is 65 Kg.

Answer 1

Answer:

u = 36km/h = 36 x 5/18 = 10m/s

v = 0 m/s

t = 4s

Using the First Equation of Motion,

v = u + at

0 = 10 + 4a

4a = -10

a = -10/4

a = -2.5 m/s^2

Total mass = 400 + 65 = 465kg

F

= ma

= 465 x -2.5

= -1162.5N

Answer 2

Answer:

• $\sf{-1162.5N}$

Explanation:

${\underline{\underline{\sf{\red{{\bigstar}\:\:\:Given:-}}}}}$

$\tiny\:\:\:\:\bullet\:\:\:\sf\orange{ u = 36km/h = 10m/sec}\\\tiny\:\:\:\:\bullet\:\:\:\sf\green{v = 0m/s}\\\tiny\:\:\:\:\bullet\:\:\:\sf\blue{t = 4s}\\\tiny\:\:\:\:\bullet\:\:\:\sf\purple{Mass \ of \ three \ wheeler = 400kg}\\\tiny\:\:\:\:\bullet\:\:\:\sf\red{Mass \ of \ driver = 65kg}\\\tiny\:\:\:\:\bullet\:\:\:\sf\green{Total \ mass \ of \ the \ system = 465kg}$

${\underline{\underline{\sf{\orange{{\bigstar}\:\:\:ToFind:-}}}}}$

$\tiny\:\:\:\:\bullet\:\:\:\sf\purple{Average \ retarding \ force \ on \ the \ vehicle}$

${\underline{\underline{\sf{\blue{{\bigstar}\:\:\: Solution:-}}}}}$

${\red{\underline{\boxed{\sf{v = u + at}}}}}$

$\tiny{\underline{\sf{\:\:\:\:Where,\:\:\:}}}$

$\tiny\:\:\:\:\bullet\:\:\:\sf\orange{v = final \ velocity}\\\tiny\:\:\:\:\bullet\:\:\:\sf\green{u = initial \ velocity}\\\tiny\:\:\:\:\bullet\:\:\:\sf\blue{a = acceleration }\\\tiny\:\:\:\:\bullet\:\:\:\sf\red{t = time}$

$\star\:{\underline{\mathfrak{\purple{Substituting \ the \ values}}}}$

$\tiny\qquad\quad\rightarrow\:\:\:\:\sf{a = \dfrac{v-u}{t}}$

$\tiny\qquad\quad\rightarrow\:\:\:\:\sf{a = \dfrac{0-10}{4}}$

$\tiny\qquad\quad\rightarrow\:\:\:\:\sf{a = -2.5m/s^2}$

${\red{\underline{\boxed{\sf{F= ma}}}}}$

$\tiny{\underline{\sf{\:\:\:\:Where,\:\:\:}}}$

$\tiny\:\:\:\:\bullet\:\:\:\sf\orange{F = force}\\\tiny\:\:\:\:\bullet\:\:\:\sf\green{m = mass \ of \ the \ body}\\\tiny\:\:\:\:\bullet\:\:\:\sf\blue{a = acceleration}$

$\tiny\qquad\quad\rightarrow\:\:\:\:\sf{F = 465\times (-2.5) }$

$\tiny\qquad\quad\rightarrow\:\:\:\:\sf{F = -1162.5N}$