Question

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?

Answer 1

`"average"` `"acceleration"` `= 2 7/9 \ "m/s"^2`

Explanation:

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

`a=(v-u)/t`

where

• `a= "acceleration"`
• `v= "final velocity"`
• `u= "initial velocity"`
• `t= "time taken"`

Here

`"70 km/h" = "70 km"/"1 h" * "1 h"/"3600 s" * "1000 m"/"1 km" = 19 4/9 \ "m/s"`

From the question

• `u = "0 m/s"`
• `v= 19 4/9 \ "m/s"`
• `t = "7 s"`

So

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

`a = 2 7/9 \ "m/s"^2`