• Support PF! Buy your school textbooks, materials and every day products Here!

Traffic signal physics problem

  • Thread starter brad sue
  • Start date
281
0
Hi,
this is a problem I have . But because I cannot include the graph, I try to do via Microsoft Word. I put it as an attachment. I hope that you will understand it.

This is the problem:

Traffic signals are placed along a straight road at positions x = 0 m, x = 600 m, and x = 1200 m (see graph in attachment)). The time intervals during which the signals are green are shown by the thick lines ( in red) in the figure.

(a) Draw the displacement-versus-time curves (fastest and slowest) for a car that passes through all the lights when the car moves with constant speed.

(b) Draw a similar set of lines for a car traveling in the opposite direction.

(c) Assuming that the lights are timed such that a car passes through all lights in the middle of the time interval, what is the speed for which the lights are timed?

(d) What is the fastest constant speed of a car that makes it through all the signals, assuming it arrives at the first light at the optimal moment?

For info.:
The grah is a 2 dimension space with time(s) on horizontal and the position x(m) in vertical.
The interval are put in red and I mentioned the time interval at the end of each line.
Please help me with that . I do not understand it

Thank you very much.

Brad
 

Attachments

Answers and Replies

Astronuc
Staff Emeritus
Science Advisor
18,543
1,685
Well if you map x=x(t), then v = dx/dt and the slope is speed (or magnitude of velocity).

If you draw a straight line, it's slope will be a constant speed.

So the fastest speed, will have the steepest slope.
 
281
0
ok!

Thank you that make more sense now , but what about quesion c

I do not understand this question .
Thanks

Brad
Astronuc said:
Well if you map x=x(t), then v = dx/dt and the slope is speed (or magnitude of velocity).

If you draw a straight line, it's slope will be a constant speed.

So the fastest speed, will have the steepest slope.
 

Related Threads for: Traffic signal physics problem

  • Last Post
Replies
2
Views
12K
  • Last Post
Replies
12
Views
6K
Replies
4
Views
675
Replies
1
Views
917
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
2
Views
3K
  • Last Post
Replies
3
Views
7K
Replies
1
Views
1K
Top