Answer:
The time = 74.61 s.
Explanation:
From Newton's Third law of motion,
The force needed to stop is equal and opposite to the propelling force from the engine of the freight car.
F = ma ........................ Equation 1
Where F = force needed to stop the the freight car, m = mass of the freight car, a = acceleration of the freight car.
a = F/m....................... Equation 2.
Given: F = - 1150 N(Opposite in direction to the motion of the car) m = 26000 kg.
Substituting into equation 2
a = -1150/26000
a = -0.04423 m/s²
Also
v = u + at
t = (v-u)/a.................... Equation 3
Where t = time needed for the force to stop the car, v = final velocity, u = initial velocity, a = acceleration.
Given: u = 3.3 m/s v = 0 m/s (brought to rest), a = -0.04423 m/s²
Substituting into equation 3
t = (0-3.3)/-0.04423
t = -3.3/0.04423
t = 74.61 sec.
Thus the time = 74.61 s
