Question

A car moving at 72 kmph is to be stopped by applying brakes in the next 10m. If the car weights 1000 kg. The average force applied on the car is​

Answer 1

        $\text{The following parameters are given:}$

        $\text{Initial Velocity}(u) = 72 \: km/h = 20 \: m/s$

        $\text{Displacement}(s) = 10 \: m$

        $\text{Final Velocity}(v) = 0 \: m/s$

        $\text{Mass of Car}(m) = 1000 \; kg$

        $\text{Applying the 3rd equation of motion i.e }v^2 - u^2 = 2as$

$\implies \: -400 = 20a$

$\implies \: a = -20 \: m/s^2$

        $\text{We know that Force}(F) = ma$

$\implies \: F = 1000 \times (-20)$

$\implies \: \boxed{F = -20000 \: N}$