A train of mass of 6.84*10^6 kg is moving at a speed of 80 km/h. The brakes, whi
ID: 1292944 • Letter: A
Question
A train of mass of 6.84*10^6 kg is moving at a speed of 80 km/h. The brakes, which produce a net backwards force of 1.93*10^6 N, are applied for 25.0 seconds. A) What is the new speed of the train? B) How far has the train traveled in this time? A train of mass of 6.84*10^6 kg is moving at a speed of 80 km/h. The brakes, which produce a net backwards force of 1.93*10^6 N, are applied for 25.0 seconds. A) What is the new speed of the train? B) How far has the train traveled in this time? A) What is the new speed of the train? B) How far has the train traveled in this time?Explanation / Answer
mass = 6.84 * 10^6 kg
F = ma
-1.93 * 10^6 = 6.84 * 10^6 * a
a = -0.282 m/s^2
t = 25 s
u = 80 km/h = 80 * 5/18 = 22.222 m/s
v = u + at
v = 22.222 - (0.282) * 25
= 15.172 m/s
= 54.62 km/hr
b)
v^2 - u^2 = 2as
15.172^2 - 22.222^2 = 2 * ( -0.282) * s
s = 467.425 metres