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A car is travelling at a …

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A car is travelling at a speed of 30 km/h is brought to rest in a distance of 8 m by applying brakes. If the same car is moving at a speed of 60 km/h then it can be brought to rest with the same brakes in what distance?

  • 2 answers

Arpan Bhowmick 6 years, 8 months ago

33.3 m

Sahdev Sharma 6 years, 8 months ago

First case

Initial velocity u = 30 km/h {tex}= {25\over 3}\ m/s{/tex}

As it stops so Final velocity v = 0

time taken t  = 8 m

Acceleration of car = a 

We know,

{tex}a = {v-u\over t}{/tex}

={tex}-{25\over 24}\ m/s^2{/tex}

Second case : 

As same breaks applied so acceleration is same.

initial velocity u = 60 km/h {tex}={50\over 3}\ m/s{/tex}

As it comes to rest so final velocity v = 0 m/s

Distances covered before rest = s

We know,

{tex}v^2-u^2= 2as{/tex}

=> {tex}(0)^2-({50\over 3})^2= 2\times {-25\over 24}\times s{/tex}

{tex}=> s =-{2500\over 9}\times {-24\over 25}\times {1\over 2}{/tex}

= 33.3 m

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