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

Related rates falling rock with shadow

  • Thread starter cragar
  • Start date
  • #1
2,544
2

Homework Statement


a light shines from the op of a pole 50ft high a ball is dropped from the same height from a point 30 feet away from the light , how fast is the shadow of the ball moving along the ground .5second later.


So is the ball falling at 32ft/s^2
would we set it up like 50/x=y/(x-30)
x is the distance from the light pole to the end of the shadow and y is the heidght of the ball above the ground . is the balls rate 32t then we would take the deravative and plug every thing in , is my setup right .
 

Answers and Replies

  • #2
tiny-tim
Science Advisor
Homework Helper
25,832
249
Hi cragar! :wink:
a light shines from the op of a pole 50ft high a ball is dropped from the same height from a point 30 feet away from the light , how fast is the shadow of the ball moving along the ground .5second later.

would we set it up like 50/x=y/(x-30)
x is the distance from the light pole to the end of the shadow and y is the heidght of the ball above the ground . is the balls rate 32t then we would take the deravative and plug every thing in , is my setup right .
Yes, that's fine! :smile:

Just one improvement …

you've used similar triangles,

but since the speed is 0 at the top, it will save time if instead of y you use the height of the ball below the top, and use a different pair of similar triangles :wink:
 

Related Threads for: Related rates falling rock with shadow

  • Last Post
Replies
3
Views
794
  • Last Post
Replies
4
Views
2K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
5
Views
5K
  • Last Post
Replies
9
Views
4K
  • Last Post
Replies
1
Views
9K
  • Last Post
Replies
1
Views
4K
Replies
2
Views
4K
Top