- #1
phosgene
- 146
- 1
Homework Statement
A meat baster consists of a flexible bulb attached to a plastic tube as shown in the diagram. When the open end of the tube is immersed in the basting sauce and the bulb is squeezed then released, sauce rises in the tube so that it can be squirted over the meat. Suppose sauce rises in the tube to a height h of 0.12m. Assume that the density of the sauce is 1050 kg/m^3
(c) Calculate the absolute pressure of the air in the bulb when atmospheric pressure is 1.010 x 10^5 Pa
Homework Equations
Bernoulli's equation to calculate pressure difference between bottom and top points of the height the sauce rises.
The Attempt at a Solution
I calculated the pressure difference betewen the start and end point of the measured height:
P = pg(y2 - y1)
P = (1050 kg/m^3)(9.8 m/s^2)(0.12 m)
P = 100.8 Pa
I'm not really sure how to answer the question, but here's my attempt:
If the sauce isn't rising anymore, then the forces acting on it should be in equilibrium, cancelling each other out. The liquid's force will be directed downward, out of the baster, the atmospheric force will be directed upward, into the baster, and the force of the air inside the baster will be directed downward (pushing the sauce out of the baster). So the atmospheric pressure should be the same magnitude as the other two pressures.
If I do the calculation, I get the absolute pressure of the air in the bulb being 1.010 x 10^5 Pa - 100.8 Pa
But I'm not really sure.