A car advertisement states that a certain car can accelerate from rest to 70 km/h in 7 seconds. What is the car's average acceleration?

Jan 1, 2016

$\text{average}$ $\text{acceleration}$ $= 2 \frac{7}{9} \setminus {\text{m/s}}^{2}$

Explanation:

The acceleration of an object can be calculated based on the formula

$a = \frac{v - u}{t}$

where

• $a = \text{acceleration}$
• $v = \text{final velocity}$
• $u = \text{initial velocity}$
• $t = \text{time taken}$

Here

$\text{70 km/h" = "70 km"/"1 h" * "1 h"/"3600 s" * "1000 m"/"1 km" = 19 4/9 \ "m/s}$

From the question

• $u = \text{0 m/s}$
• $v = 19 \frac{4}{9} \setminus \text{m/s}$
• $t = \text{7 s}$

So

a = (19 4/9 \ "m/s" - "0 m/s") / "7 s"

$a = 2 \frac{7}{9} \setminus {\text{m/s}}^{2}$