How far will the train travel while it is stopping?
December 30, 2009 - Posted in travel train
A train has a mass of 3.2*10^6 kg. What steady breaking force must be applied to the wheels of the train to bring it to a stop in 12 mins if it is initially traveling at a speed of 60 km/hr? How far will it travel while it is stopping?
I believe this is a frictionless problem…but I don’t know where to being with this problem.
Let:
m be the mass of the train,
a be its acceleration (negative for deceleration),
s be the stopping distance,
t be the stopping time,
F be the braking force,
u be the initial speed,
v be the final speed.
F = ma …(1)
v = u + at …(2)
60 km/hr = 60000 / 3600 = 50 / 3 m/s.
12 min = 720 sec.
Eliminating a from (1) and (2):
F = m(v – u) / t
= 3.2 * 10^6( 0 – 50 / 3) / 720
= – 7.41 * 10^4 N to 3 sig. fig.
F is negative as it is opposing the motion.
s = t(u + v) / 2
= 720(50 / 3 + 0) / 2
= 6000 m.
One Response to “How far will the train travel while it is stopping?”
Let:
m be the mass of the train,
a be its acceleration (negative for deceleration),
s be the stopping distance,
t be the stopping time,
F be the braking force,
u be the initial speed,
v be the final speed.
F = ma …(1)
v = u + at …(2)
60 km/hr = 60000 / 3600 = 50 / 3 m/s.
12 min = 720 sec.
Eliminating a from (1) and (2):
F = m(v – u) / t
= 3.2 * 10^6( 0 – 50 / 3) / 720
= – 7.41 * 10^4 N to 3 sig. fig.
F is negative as it is opposing the motion.
s = t(u + v) / 2
= 720(50 / 3 + 0) / 2
= 6000 m.
References :
By Rackbrane on Dec 30, 2009