Car acceleration calculation problem

Click For Summary

Homework Help Overview

The problem involves a car accelerating towards a train that is moving at a constant speed. The car starts behind the train and is tasked with determining its speed at the moment it passes the train.

Discussion Character

  • Exploratory, Problem interpretation, Assumption checking

Approaches and Questions Raised

  • Participants discuss using equations of motion to relate the distances traveled by both the car and the train. There are attempts to establish a relationship between the two objects' positions over time and to find a common time when the car passes the train.

Discussion Status

Some participants have suggested setting up equations for the distances of both the car and the train and equating them to find the time at which the car catches up. However, there is uncertainty about how to apply these equations effectively, particularly in terms of understanding the conditions for when the car passes the train.

Contextual Notes

Participants note the initial conditions, including the initial distance between the car and the train, as well as the speeds and acceleration involved. There is mention of needing to account for the displacement between the two vehicles.

AraProdieur
Messages
27
Reaction score
0

Homework Statement


A train is moving parallel and adjacent to a highway with a constant speed of 33 m/s. Initially a car is 32 m behind the train, traveling in the same direction as the train at 47 m/s and accelerating at 4 m/s^2.
What is the speed of the car just as it passes the train? Answer in units of m/s.



Homework Equations


So far, I have thought of using delta x= volt+ 1/2at^2
I also think that I have to account for the displacement between the two trains, which is 14 m.
The thing that I don't understand is how to calculate something as it passes or catches up to another thing.

If there is any advice, thanks!
 
Physics news on Phys.org
Let the point when the measurement starts be s=0, then you have all the initial conditions. Now consider the distance s as a function of time t, so s(0)=0 for the car and s(0)=32 for the train. Write two such formulae, one to describe each object. At the point where the car passes the train, the two distances are the same, so you can equate and get a time value t_{m}, where then you can calculate the speed of the car with the formulae describing uniform acceleration.
 
bel said:
Let the point when the measurement starts be s=0, then you have all the initial conditions. Now consider the distance s as a function of time t, so s(0)=0 for the car and s(0)=32 for the train. Write two such formulae, one to describe each object. At the point where the car passes the train, the two distances are the same, so you can equate and get a time value t_{m}, where then you can calculate the speed of the car with the formulae describing uniform acceleration.

Yes, but I don't understand how to go about doing that. Like getting the two distances to equal the same? I did think of that as well, but didn't know how to use formulas to do something like that.
 
Say, for the train, which is initially (i.e., at time t=0) 32 metres ahead of the car, and travels with a constant velocity, say v_{train}. Then we have for the train s=32+v_{train}t.
 

Similar threads

Replies
20
Views
2K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 7 ·
Replies
7
Views
1K
  • · Replies 3 ·
Replies
3
Views
5K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 2 ·
Replies
2
Views
1K
Replies
9
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K