# Homework Help: Physics pressure problem

1. Jun 7, 2005

### briandeblis

Have a dilemma on this problem:
An ice cube, density = 917 kg/m^3, is sliding down a frictionless incline of 16 degrees. The sides of the cube each have a length of 0.75 m. What pressure does the cube exert on the incline?

Any help out there?

2. Jun 7, 2005

3. Jun 7, 2005

### briandeblis

response

a downward force due to mass and gravity?

4. Jun 8, 2005

### Pyrrhus

What force does the cube exerts on the incline? and what side (surface) in the cube it's in contact with the incline?

5. Jun 8, 2005

### briandeblis

It exerts its weight and it is the bottom side

6. Jun 8, 2005

### ZapperZ

Staff Emeritus
You really haven't managed to come up with the exact definition of "pressure". You may want to consider finding this out first.

Zz.

7. Jun 8, 2005

### briandeblis

pressure is the force exerted on a surface divided by the area of the surface to which it is applied

8. Jun 8, 2005

### ZapperZ

Staff Emeritus
So, to get pressure, first find the FORCE exerted on the surface in question. You already know the surface area.

Zz.

9. Jun 8, 2005

### briandeblis

Well, FORCE = Mass * gravity , right?

10. Jun 8, 2005

### ZapperZ

Staff Emeritus
Note that the object is on an INCLINED plane. You need to look back at problems/examples/etc. of mass on inclined plane.

Zz.

11. Jun 8, 2005

### briandeblis

So the FORCE = m*g*cos (theta) right?

12. Jun 8, 2005

### Pyrrhus

Yes., Now find the mass.

13. Jun 8, 2005

### briandeblis

mass = density * volume ?

14. Jun 8, 2005

### Pyrrhus

Yes, Now solve the problem.

15. Jun 8, 2005

### briandeblis

Thanks. I have it now. The class I am taking is an online class and they don't give very good examples to work on before the tests which are very hard problems.

16. Jun 8, 2005

### Pyrrhus

No problem, just remember if there's a word you don't understand, look up its definition, and Welcome to PF!