Density and Pressure

Formula for Density

Density = Mass/Volume

Formula for pressure

Force/Area

Formula for pressure in a fluid

Change in pressure = density x gravity x change in height

Archimedes principle

When an object is immersed in a fluid, the upthrust it experiences is equal to the weight of the displaced fluid.

The law of flotation

The weight of a floating object is equal to the weight of the fluid it displaces.

Boyle’s Law

At constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure.

Formula for Boyle’s Law

(p1)(v1)=(p2/)(v2)

Describe an experiment to prove archimedes principle.

1. Find the weight of an object and a beaker on a newton Balance.

2. Find the up thrust of a weight in water by subtracting the weight before the object is in water by the weight of the object in water.

3. Weigh a beaker of displaced water with an electronic balance and it should equal the upthrust.

Why does a steel bar sink when placed in water?

Because the weight of the steel bar is greater than the weight of water it displaces meaning the upthrust it experiences is less than its weight..

A boat made of mostly steel floats on water. Why?

Because the density of the boat and its contents is less than the density of water. This means that the weight of the boat is equal to the weight of the water it displaces and therefore it floats.