Question

The initial velocity of a car which is stopped in 10 second by applying brakes. The acceleration due to brakes is 2.5 m/s²​

Answer 1

$\large\sf\underline{Understanding\:the\:question\::}$

Here a car is moving with some velocity. Then after some time the driver stops the car. He applies an acceleration of about 2.5 m/s². The car takes 10sec to come at rest after the application of brake . We are asked to find the initial velocity of that car . We will use kinematical equation and solve this problem. Let's begin !

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$\large\sf\underline{Given\::}$

• Final velocity , v = 0 m/s ( car is stopped )

• acceleration , a = -2.5 m/s² ( negative because it is retardation )

• Time , t = 10 s

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$\large\sf\underline{To\:find\::}$

• Initial velocity , u = ?

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$\large\sf\underline{Solution\::}$

Using the first equation of motion :

$\large{\underline{\boxed{\mathrm\pink{v\:=\:u+at}}}}$

where ,

• v = Final velocity

• u = initial velocity

• a = acceleration

• t = time

Substituting the given values in the formula :

$\sf\implies\:0 = u +(-2.5) \times 10$

$\sf\implies\:0 = u - 2.5 \times 10$

$\sf\implies\:0 = u - 25$

$\sf\:oR\: u - 25=0$

$\large{\mathfrak\red{\implies\:u\:=\:25\:m/sec}}$

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$\dag\:\underline{\sf So\:initial\:velocity\:is\:25\:m/sec}$

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!! Hope it helps !!

Answer 2

${\orange{\bigstar}} \ {\underline{\green{\textsf{\textbf{Given :-}}}}}$

• Final velocity , v = 0 m/s ( car is stopped )
• acceleration , a = -2.5 m/s² ( negative because it is retardation )
• Time , t = 10 s

${\blue{\bigstar}} \ {\underline{\pink{\textsf{\textbf{To Find :-}}}}}$

Initial velocity , u = ?

${\purple{\bigstar}} \ {\underline{\red{\textsf{\textbf{To Find :-}}}}}$

‎Using the first equation of motion :

$\large{\underline{\boxed{\mathrm\pink{v\:=\:u+at}}}}$

where ,

v = Final velocity

u = initial velocity

a = acceleration

t = time

Substituting the given values in the formula :

$\sf\implies\:0 = u +(-2.5) \times 10$

$\sf\implies\:0 = u - 2.5 \times 10$

$\sf\implies\:0 = u - 25$

$\sf\:oR\: u - 25=0$

$\large{\mathfrak\red{\implies\:u\:=\:25\:m/sec}}$

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