Question

A car driver traveling 40 m/s slows down to a speed of 20 m/s in 10 seconds. What is the car’s acceleration?

Answer 1

the answer to this question is

-2 per second

Answer 2

The equation we use is to determine the acceleration of the car, it is a Uniformly Varied Rectilinear Motion (MRUV) is:

             $\boxed{\sf{a=\dfrac{V_{f}-V_{o}}{t}}} \ \ \ \ \ \sf{\longmapsto \ \ \ \ \ Where \ \ \ \ \begin{cases}\sf{V_{f} = Final \ velocity} \\ \sf{V_{o}=Initial \ velocity} \\ \sf{a=Acceleration} \\ \sf{t=Time} \end{cases}}$

We extract the data of the problem:

• $\sf{V_{f}=20 \ m/s}$

• $\sf{V_{o}=40 \ m/s}$

• $\sf{t=10 \ s}$

We plug these values into the scalar equation above.

                                         $\sf{a=\dfrac{V_{f}-V_{o}}{t}}$

                                   $\sf{a=\dfrac{20 \ m/s-40m/s}{10 \ s} }$

                                          $\sf{a=\dfrac{-20 \ m/s}{10 \ s} }$

                                         $\boxed{\boxed{\boldsymbol{\sf{a=-2 \ m/s^{2} }}}}$

Rpta: The acceleration of the car was -2 m/s^2.