Question

A car decreases its velocity from 80 $kmh{r}^{-1}$ to 60 $kmh{r}^{-1}$ in 5 seconds. The acceleration of the car is

• A. -1.11 m/s²
• B. 1.12 m/s²
• C. -1.14 m/s²
• D. 1.11 m/s²

Answer 1

The correct option is A

-1.11 m/s²

Here,

Initial velocity, $u=80kmh{r}^{-1}=80\times \frac{5}{18}=22.22m{s}^{-1}$

Final velocity, $v=60kmh{r}^{-1}=60\times \frac{5}{18}=16.67m{s}^{-1}$

Time, $t=5s$

Using, $a=\frac{v-u}{t}$, we get,

$a=\frac{16.67-22.22}{5}m{s}^{-2}$

$=-1.11m{s}^{-2}$