the force applied divided by the surface area pressure = force/area force (or weight) of an object...
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PRESSURE The force applied divided by the
surface area Pressure = Force/Area Force (or weight) of an object
depends on its mass and the pull of gravity
Area – the total surface of an objectLength (m) x width (m)Unit used is meter squared (m2)
THE RELATIONSHIP…
As force increases, pressure also increases – directly proportional
As area increases, pressure decreases – indirectly proportional
Just like pressure is exerted on your foot- gas molecules exert pressure on things too.
Pressure can be measured in many different units:
Inches of mercuryPounds per square inch (psi)Millimeters of mercury (mmHg)
Atmospheres (atm)
That’s a lot of different units for one thing!!
HOW DO SCIENTISTS COMMUNICATE?
Certain units are used in scientific measurements
International System of Units (SI) – lets scientists all over the world to communicate with each other.
Chart
HOW DO SCIENTISTS COMMUNICATE?
Certain units are used in scientific measurements
International System of Units (SI) – lets scientists all over the world to communicate with each other.
Chart
There are 2 different “kinds” of units:
- Base Units- Derived Units
Base Units – There are 7!!basic physical measurements (units in the metric system)
Ex: mass and length
Derived units – Must be figured out mathematically
Ex: area, force, volume and pressure
UNITS FOR FORCE AND PRESSURE
Force is measured in Newtons (N) A bar of soap pushes down with
about 1N of force.
Pressure is measured in Pascals (Pa) Pascal (Pa) = N/m2
To find pressure need 2 things:1. Force (units = N)2. Area (units = m2)
CONCEPT CHECK:
Photo shows two bricks of the same mass lying on the ground. 1. Is each brick exerting the same total force on the ground? Explain.
2. Is each brick exerting the same pressure on the ground? Explain.
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