Gradient / Velocity

  • Thread starter Doc G
  • Start date
  • #1
Doc G
18
0
Ok, this may sound a little basic but I can’t think of a way of explaining it other than common sense. I should also say that this is for a Geography assignment so not really physics but hope you guys can give me an insight.

I’m trying to explain why the steeper the gradient of a river, the faster the water flows.

I was thinking that it must be something to do with friction but then wondered whether an object on a ramp angled at 45 degrees in a frictionless environment would accelerate at gravity and I’m not too sure. :confused:

Any help in explaining it would be great
Thanks in advance
 

Answers and Replies

  • #2
marlon
3,777
11
Doc G said:
I was thinking that it must be something to do with friction but then wondered whether an object on a ramp angled at 45 degrees in a frictionless environment would accelerate at gravity and I’m not too sure. :confused:

yes it would, though the acceleration will not be equal to g but a bit less. It really depends on the angle of the incline

Also, rigid body mechanics will teach you that the acceleration at which an object rolls of does not depend on the magntude of the object, also not on the mass but on the way the mass is distributed throughout the object's volume. This is expressed by the socalled mass tensor or the socalled rotational inertia (I-tensor). For example, two equally big and heavy spheres will roll down at different accelerations if their mass is distributed differently when compared to each other.

marlon
 
  • #3
LENIN
102
1
Try think of the river as a singel massive point. In this way you can think of it s a vlock on a slope insted of a liquid. You can than simmpaly excamen the problem with forces. There are 2 forces the force of gravity and the force of the ground (it may help to draw this). The force of gravity can than be divided into 2 others. One parallel to the slope and onathe having a -90 deggres angel to it. The one parralel to the slope is the one responsable for the movment of the block (river). Friction does reduce the speed by some factor. But in this very basic explination we don't really need to think about it.

I hope this helps.
 
  • #4
marlon
3,777
11
Doc G said:
Any help in explaining it would be great
Thanks in advance

If want, i have written a little tutorial on Newtonian Physics . It also covers problems related to inclines. Also, look at the sample problems

ENJOY

regards
marlon
 
  • #5
Doc G
18
0
Thank you both very much for your replies. I'll try to get my head aroud it as I'm probably still a couple of years off learning this in physics. Though if I combine your two replies I'm sure my geography teacher will be impressed :smile:
 

Suggested for: Gradient / Velocity

  • Last Post
Replies
5
Views
2K
  • Last Post
Replies
2
Views
206
Replies
2
Views
382
  • Last Post
Replies
2
Views
449
  • Last Post
Replies
18
Views
421
  • Last Post
Replies
17
Views
783
Replies
2
Views
319
Replies
9
Views
471
Replies
9
Views
570
  • Last Post
Replies
7
Views
288
Top