Question

4 A car moves at a constant velocity of 30 m/s and has 3.6 x 10*5J of kinetic
energy. The driver applies the brakes and the car stops in 95 m.
Calculate the force needed to stop the vehicle.

Answer 1

Answer:

To find the force we need mass and acceleration so let's find them first

$\frac{1}{2} m {v}^{2} = 3.6 \times {10}^{5} \\ \frac{1}{2} \times m \times 900 = 3. {10}^{5} \\ m = 800kg$

${v}^{2} = {u}^{2} + 2as \\ 0 = 900 - 2a(95) \\ a =4.7m {s}^{ - 2}$

$f = ma \\ f= 800 \times 4.73 \\ f= 3784n$