A train that is momentarily at rest, Newton's Laws

AI Thread Summary
A train traveling up a 3.73-degree incline at 3.25 m/s has its last car break free and coast without friction. To determine how long it takes for the last car to come to rest and the distance it travels before stopping, the acceleration must be calculated using the gravitational force component along the incline. The key point is that gravity is the only force acting on the car after it is released, allowing for the use of sine to find the acceleration. Understanding the relationship between velocity, acceleration, and distance is crucial for solving the problem. The discussion emphasizes the importance of correctly applying Newton's laws to analyze the motion of the car.
cloudage
Messages
14
Reaction score
0

Homework Statement


A train is traveling up a 3.73 degrees incline at a speed of 3.25 m/s when the last car breaks free and begins to coast without friction.
a) How long does it take for the last car to come to rest momentarily?
b) How far did the last car travel before momentarily coming to rest?


Homework Equations





The Attempt at a Solution


I tried to draw the free body diagram, but since I have either mass or a force I don't know how to proceed. Momentarily at rest means that it's velocity is zero, but I don't know it's acceleration after the car has been released so I can't use the kinematics.
 
Physics news on Phys.org
cloudage said:

Homework Statement


A train is traveling up a 3.73 degrees incline at a speed of 3.25 m/s when the last car breaks free and begins to coast without friction.
a) How long does it take for the last car to come to rest momentarily?
b) How far did the last car travel before momentarily coming to rest?


Homework Equations





The Attempt at a Solution


I tried to draw the free body diagram, but since I have either mass or a force I don't know how to proceed. Momentarily at rest means that it's velocity is zero, but I don't know it's acceleration after the car has been released so I can't use the kinematics.
After the car is released, you should be able to find its acceleration. What net force acts on the car when it is released?
 
I got it, thank you very much! It would just be gravity acting on it, so I can find the component by using sine. Thanks!
 
cloudage said:
I got it, thank you very much! It would just be gravity acting on it, so I can find the component by using sine. Thanks!
Yes, and welcome to PF!
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

Solving for a Train Without Knowing Mass
Replies
1
Views
2K
Train travelling uphill at s.7s degree incline, find friction coefficient
Replies
10
Views
9K
Train on 4.4 Incline: Solving for Momentary Rest
Replies
2
Views
2K
Vector force conceptual exercise help.
Replies
2
Views
3K
Speed of train car when sand spilling out from it
Replies
17
Views
4K
How Do You Convert Newtons to Watts for a Maglev Train Acceleration?
Replies
5
Views
7K
Newton's law problem: Pushing 2 stacked blocks on a horizontal table
Replies
13
Views
3K
How Do You Calculate Force and Distance in Physics Problems?
Replies
2
Views
4K
What is the displacement of a 3.0 kg block sliding down an inclined plane?
Replies
12
Views
2K
Finding friction and tension for a train
Replies
1
Views
2K

Hot Threads

Recent Insights

Back
Top