Question

A car moving with a a velocity of 40 m/s suddenly applies brakes and comes to rest in next 5 seconds calculate the retardation produced in the car after the application of the brakes​

Answer 1

Provided that:

• Initial velocity = 40 m/s
• Final velocity = 0 m/s
• Time taken = 5 seconds

Don't be confused! Final velocity cames as zero because brakes applied to a moving car to bring it at rest.

To calculate:

• The retardation

Solution:

• The retardation = -8 m/s²

Using concept:

• Acceleration formula

Using formula:

• ${\small{\underline{\boxed{\sf{a \: = \dfrac{v-u}{t}}}}}}$

Full solution:

$:\implies \sf a \: = \dfrac{v-u}{t} \\ \\ :\implies \sf a \: = \dfrac{0-40}{5} \\ \\ :\implies \sf a \: = \dfrac{-40}{5} \\ \\ :\implies \sf a \: = \cancel{\dfrac{-40}{5}} \\ \\ :\implies \sf a \: = -8 \: ms^{-2} \\ \\ :\implies \sf Acceleration \: = -8 \: ms^{-2} \\ \\ :\implies \sf Retardation \: = -8 \: ms^{-2}$

Therefore, -8 m/s² is retardation produced by the car after the application of the brakes.

• Dear app users, you can see step of cancelling from attachment 1st

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About acceleration:

$\begin{gathered}\boxed{\begin{array}{c}\\ \bf What \: is \: acceleration? \\ \\ \sf The \: rate \: of \: change \: of \: velocity \: of \: an \\ \sf object \: with \: respect \: to \: time \\ \sf is \: known \: as \: acceleration. \\ \\ \sf \star \: Negative \: acceleration is \: known \: as \: deacceleration. \\ \sf \star \: Deacceleration \: is \: known \: as \: retardation. \\ \sf \star \: It's \: SI \: unit \: is \: ms^{-2} \: or \: m/s^2 \\ \sf \star \: It \: may \: be \: \pm ve \: or \: 0 \: too \\ \sf \star \: It \: is \: a \: vector \: quantity \\ \\ \bf Conditions \: of \pm ve \: or \: 0 \: acceleration \\ \\ \sf \odot \: Positive \: acceleration: \: \sf When \: \bf{u} \: \sf is \: lower \: than \: \bf{v} \\ \sf \odot \: Negative \: acceleration: \: \sf When \: \bf{v} \: \sf is \: lower \: than \: \bf{u} \\ \sf \odot \: Zero \: acceleration: \: \sf When \: \bf{v} \: \sf and \: \bf{u} \: \sf are \: equal \end{array}}\end{gathered}$