94 kilometers per hour equals 94000 meters per 3600 seconds or 26.111111111 (m/s).
The Kinetic Energy of the car at 26.111111111 (m/s) is given by (1/2)mv2 or (1/2)(3100 kg) times (26.111111111)2(m2/s2).
Equating the Kinetic Energy Of The Car to Work Done In Braking gives (1/2)(3100 kg) times (26.111111111)2(m2/s2) = Stopping Force Applied Through The Braking Distance or Force In Newtons (F) times 50 meters, where a Newton is 1 kilogram "dot" meter per second2.
Then F = (1/2)(3100 kg)(26.111111111)2(m2/s2) divided by (50 m). This simplifies to 21135.49383 (kg•m/s2 or N).
1 Newton will convert to 0.2248 pounds.
ANOTHER METHOD:
Write (velocitystopped)2 = (velocitymoving)2 + 2(abraking)(xdistance to stop) which, in this case, gives 02 = (26.111111111)2 (m2/s2)+ 2(deceleration of car in m/s2 while braking)(50 m). This gives abraking (or the slowing rate of the car) as -(26.111111111)2/100 or -6.817901234 m/s2, the negative sign indicating a deceleration or slowing of the car.
Multiply -6.817901234 m/s2 by 3100 kg to obtain -21135.49383 (kg•m/s2 or Newtons), the negative sign again indicating a slowing or opposing force to the car's initial velocity.
