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

Pressure of Falling Sand

  • Thread starter dmark312
  • Start date
  • #1
1
0

Homework Statement



Grains of sand of mass 2.90x10^-3 g each, fall from a height of 0.5 m on a sticky surface at a rate of 45 grains per second per cm^2. What pressure does this shower of sand exert on the surface, assuming that air resistance can be neglected?

Homework Equations



p=F/A=mv^2(N/V)

The Attempt at a Solution


I don't know where to start. Anyone care to point me in the right direction?
 

Answers and Replies

  • #2
111
0
You can work out the velocity with which every grain of sand lands. You also know what total mass of sand falls per second. Your force, [itex]F[/itex], is equal to the force required to accelerate that certain mass of sand by that certain velocity in one second.
 
  • #3
Redbelly98
Staff Emeritus
Science Advisor
Homework Helper
Insights Author
12,100
129
Welcome to PF :smile:

P = F / A is definitely useful here.

Also of use is

F = Δp / Δt

where little p is momentum (not pressure). You'll need to figure out the change in momentum, for the total of all grains of sand that hit a square cm of the surface, in 1 second.
 

Related Threads on Pressure of Falling Sand

  • Last Post
Replies
4
Views
2K
Replies
1
Views
1K
Replies
13
Views
6K
Replies
1
Views
2K
  • Last Post
Replies
2
Views
5K
  • Last Post
Replies
2
Views
1K
Replies
2
Views
4K
  • Last Post
Replies
6
Views
2K
  • Last Post
Replies
4
Views
6K
  • Last Post
2
Replies
32
Views
5K
Top