First, calculate the decceleration experienced by the car, by using Newton Secon Law:
F = m*a
a = F/m
F: braking force = 10,000 N
m: mass of the car = 2000 kg
Replace the previous values into the expression for a:
a = 10,000N/2,000kg
a = 5 m/s^2
Next, use the following formula to find the speed of the car before the breaks were applied:
v = vo - at the second term is negative because the car is deccelerating
vo: initial velocity
v: final velocity = 0m/s
a: acceleration = 5 m/s^2
t: time = 6 s
Solve the equation above for vo and replace the values of the ohter parameters:
vo = v + at
vo = 0 m/s + (5 m/s^2)(6 s)
vo = 30 m/s
vo = 30 m/s is the speed of the car before the breaks were applied
