Question

A car is moving with a uniform velocity of 30m/s. It is stopped in 2s by applying a force of 1500N. ​

Answer 1

Given-

☛Initial Velocity = 30m/s

☛Force = 1500N

☛Time = 2s

☛Final velocity= 0m/s

Find-

☛Change in momentum

☛Mass of the Car

Formulas used-

• $\sf{ a= \dfrac{v-u}{t}}$
• $\sf{F= m\times a}$
• $\sf{ p= m(v-u)}$

where,

a= acceleration,

v= final velocity

u= initial velocity

F= force,

m= mass,

p= change in momentum.

   

SoLution-

Firstly we will find acceleration,

$\sf{ a= \dfrac{v-u}{t}}$

$\sf{ \implies a= \dfrac{0-30}{2} }$

$\sf{ \implies a= \dfrac{-30}{2} = -15 }$

a= -15m/s²

(minus sign for retardation)

☛Now for Mass,

$\sf{F= m\times a}$

Put given values,

$\sf{\implies 1500 = m \times 15 }$

 

$\sf{\implies m= \dfrac{1500}{15} }$

 

$\sf{\implies m= 100}$

☛From mass we will find the change in momentum,

$\sf{ p= m(v-u)}$

 

Put the given values in the formula we get,

 

$\sf{\implies p = 100 (0-30)}$  

 

$\sf{\implies p = -3000kgm/s}$

 

$\underline{\bf{\green{\therefore Mass \ of\ the\ car = 100kg}}}$

$\underline{\green{\bf{ And \ change \ in \ momentum = -3000kgm/s }}}$

______________________________$\heartsuit$