Acceleration problem 15

  • Thread starter Iceclover
  • Start date
  • #1
59
0
Problem:
a rock is thrown vertically with a velocity of 20m/s from the edge of a bridge 42m above the river. how long does the rock stay in the air.

Equation:
d=vt+1/2at^2

Atempt at solution:
I've actually had a couple of attempts and i came up with a bunch of crazy things. I just need a hint, or to know if im using the correct formula.
 

Answers and Replies

  • #2
cristo
Staff Emeritus
Science Advisor
8,107
73
Iceclover, please post in the homework forums in future.

Your equation for this question is correct. Please show your work, and we will be able to help.
 
  • #3
103
0
A few good helpful hints is to do this first; label what you have and what you don't have and what you're trying to find. Then look at the equations you have; use algebra to isolate a variable and these types of problems will come a lot more easily.

Using Y's since this is acting in the Y direction, not the X direction. Also, since it's acting in the Y direction there's a force at work here =). Think about it.

Y (final position):
Yo (initial position):
Vy (final velocity):
Vyo (initial velocity):
a (acceleration):
t (time):

Hint: Your starting position will usually be 0 m. Unless told otherwise through the problem. Also, you can use a string of equations to solve for things =). Such as isolate the t, and then use that t for another equation =).
 
Last edited:

Related Threads on Acceleration problem 15

Replies
2
Views
2K
  • Last Post
Replies
3
Views
1K
Replies
3
Views
6K
Replies
14
Views
3K
  • Last Post
Replies
3
Views
1K
  • Last Post
Replies
3
Views
847
  • Last Post
Replies
1
Views
3K
  • Last Post
Replies
2
Views
5K
  • Last Post
Replies
1
Views
499
Replies
0
Views
2K
Top