Question

A car of mass 480 kg moving at a speed of 54 km h is stopped by applying brakes in 10 s . Calculate the force applied by the brakes.​

Answer 1

m=480 kg

u=54 km/hr

=54*5/18

=15 m/s

v=0 m/s

t=10 sec

we know that

v=u+at

0=15+a*10

a=-1.5 m/s²

Therefore its decelerating

F=m*a

=480*(-1.5)

=-720 N

Therefore the force opposes the motion of the car and is 720 N in magnitude

Hope this helps.

Answer 2

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Formulas You Should Know

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v=u+at

F=ma

Solution To Question;-

Given That,

$m = 480 \: kg \\ u = 54 \: km/h = 54 \times \frac{5}{18} = 15 \: m/s \\ v = 0 \: m/s \\ t = 10 \: sec \\ so \: we \: know \: that \\ = > v = u + at \\ = > 0 = 15 \: + a(10) \\ = > - 15 = 10a \\ = > a = - \frac{ 15}{10} = - 1.5 \: m {s}^{2} \\ \\ \\ also \\ = > F = ma \\ = > F = 480 \times - 1.5 = - 720N$

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