Question

A motorcar is moving with a velocity of 108 km/h and it takes 4s to stop after The brakes are applied calculate the force exerted by the brakes on the motorcar of its mass along with the passengers is 1000kg

Answer 1

U = 108 km/h => 108×5/18 => 6×5 => 30 m/s
v = 0m/s
t = 4sec
therefore , a = (v-u)/t
=>a = (0-30)/4
=> a = -30/4 => -7.5 m/s²


force = mass × acceleration
force = 1000 kg × (-7.5) m/s²
force = -7500 kg m/s²
=> force = -7500 N
negative sign denotes opposing force



hope this helps

Answer 2

U = 108 km/h

Now ,We have to convert km/h into m/s

=108×5/18 => 6×5 => 30 m/s

v = 0m/s

t = 4sec

$a = \frac{v - u}{t} \\a = \frac{0 - 30}{4} \\ a = \frac{ - 30}{4} \\ a = \ -7.5 m/ {s}^{2}$
Force = mass × acceleration

Force = 1000 kg × (-7.5) m/s²

Force = -7500 kg m/s²

=> force = -7500 N

Here the negative sign denotes opposing force