Answers

2016-02-12T19:20:06+05:30
initial velocity(u) = 90 km/s = 25 m/s
time (t) = 5 sec
mass (m) = 200 kg 
final velocity (v) = 0 m/s
v = u + at 
0 = 25 + a * 5
-25 = 5 a
-5 = a
Therefore acceleration = -5m/s²
Force = mass * acceleration 
F = 200*-5
F = -1000 N
I hope it helps………..
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2016-02-12T20:49:58+05:30
Initial velocity, u = 90 km/h or 25 m/s.
Final velocity, v = 0 bcoz it stops
Mass = 200 kg
Now, force exerted by the brakes will be the acceleration they produce to stop the motorcycle.
Therefore we will use the formula, v = u+at
v= u+ at
0= 25 + a * 5
-25= a* 5
Therefore, force exerted by the brakes is -1000 N to stop the motorcycle.
-5= a
Now, force exerted = product of mass and acceleration
= 200* -5
= -1000 N

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