Question

A car mass 500kg moving at a speed of 18km/h is stopped by brakes in 10s. Calculate the force applied by the brakes.​

Answer 1

Answer:

18km/h = 5 m/s

u = 0 m/s

v = 5 m/s

a = (v-u)/t

a = 5-0/10

a = 0.5 m/s²

F = ma

F = 500×0.5

F = 250 N

hence the force applied by the brakes is 250 Newton!

hope it will help you...

Answer 2

Answer:

250 Newton

Explanation:

mass = 500 kg

u (initial velocity) = 18 km/h = 18 * $\frac{5}{18\\}$  = 5 m/s

v (final velocity) = 0km/h (since the car stops) = 0 m/s

time (t) = 10 secs

acceleration = $\frac{v-u}{t}$ = $\frac{0-5}{10}$ = (- 0.5 )  m/s² {here minus sign indicates the direction of acceleration which in this case is opposite to the direction of motion that is retardation }

Force = mass * acceleration = 500 * (- 0.5 )  = ( - 25 kg) m/s²

[The minus sign can be ignored as per wish but in later complex calculations the sign plays an important role so it is advised to build a habit of working with the signs. :> ]

Here, the answer suggests that the force applied is in the opposite direction of the motion of the car , hence the car stops eventually.

Hope it helped :>