AP Physics 1 kinematics problem

  • Thread starter pow
  • Start date
  • #1
pow

Homework Statement


The engineer of a passenger train rounding a curve at 30m/s sights a slow-moving freight train 200m ahead on the same track travelling in the same direction with a constant velocity of 10m/s. The engineer of the passenger train immediately applies the brakes, causing a constant deceleration of 1m/s2, while the freight train continues on with a constant speed.

What distance will the passenger train travel before the collision takes place?
Passenger train
Do= 0m
D= ?
Vo= 30 m/s
V = 0
a = -1m/s^2

Freight train
Do= 200m
D= ?
Vo= 10 m/s
V = 0
a = 0m/s^2

Homework Equations


v2= 2(a)(d-do )+ vo2

3. The Attempt at a Solution

setting the equation equal to each other.
2(-1)(d-0)+302-0= 2(0)(d-200)+100-0
-2d+900=100
-2d=-800
d=400[/B]
 

Answers and Replies

  • #2
Marc Rindermann
Gold Member
30
12
it says in the problem statement that the freight train moves at a constant speed. So how is it possible that the freight train ends up with a speed ##v = 0##?
if the train moves at constant speed, is ##v^2 = a(d - d_0) + v_0^2## really a relevant equation?
 

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