Question

A car traveling at 15 m/s starts to decelerate steadily. It comes to a complete stop in 10 seconds. What is it’s acceleration

Answer 1

So the initial velocity is 15 m/s, the final velocity is 0 since it's at a complete stop and time is 10 seconds.  Therefore:

$Acceleration=\frac{v_{final}-v_{initial}}{t_{final}-t_{initial}} =\frac{0m/s-15m/s}{10s-0s} =-1.5\frac{m}{s^2}$

Therefore, the acceleration is -1.5 m/s^2.  The reason it's negative is due to the fact that the vector is going against it's original movement since it's decelerating.

Answer 2

Hello!

A car traveling at 15 m/s starts to decelerate steadily. It comes to a complete stop in 10 seconds. What is it's acceleration ?

We have the following data:

Vi (initial velocity) = 15 m/s (starts)

Vf (final velocity) = 0 m/s (stop)

t (time) = 10 s

a (acceleration) = ? (in m/s²)

We apply the data to the formula of the hourly function of the velocity, let us see:

$V_f = V_i + a*t$

$0 = 15 + a*10$

$- 15 = 10\:a$

$10\:a = - 15$

$a = \dfrac{-15}{10}$

$\boxed{\boxed{a = - 1.5\:m/s^2}}\Longrightarrow(the\:car\:slows\:down)\:\:\:\:\:\:\bf\green{\checkmark}$

Answer:  

The acceleration is -1.5 m/s² (decelerate)  

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