# A 845kg car accelerates from rest to 100km/h in 0.9 seconds. How do i calculate the average force exert on the car?

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You need to evaluate the average force hence, you need to use Newton's second law of motion, such that:

`F = m*a`

Since the problem provides the mass of the car, you need to find the acceleration such that:

`a = v/t`

You need to convert the units of measure of speed from `(Km)/h` in `m/s` such that:

`a = 100 (km)/h*1/0.9 s = 100*10^3/(3600*0.9) m/s => v = 1000/32.4 = 30.86 m/s`

Substituting `30.86` for `a` and` 845` for `m` yields:

`F = 845*30.06 => F ~~ 26080 N`

**Hence, evaluating the average force, under the given conditions, yields `F ~~ 26080 N` .**