Chapter 9 – Unit 3
Forces Influence the Motion and Properties of Fluids
Terminology
1.
Force
Anything that causes a change in the motion of an object; a
push or pull on an object
Balanced Forces
The condition in which for every force acting
on an object there is another force that is
equal in strength and opposite in direction;
the net force on the object is zero.
2.
Unbalanced Forces
The condition in which, for every force acting on an object,
there is no equal and opposite force acting on it; the net
force on an object is not zero.
3.
Weight
The measure of the force of gravity acting on the mass of an
object.
4.
Mass
The amount of matter an object has.
5.
Buoyancy
The upward force on objects submerged in (under the surface of)
or floating on a fluid.
6.
Buoyant Force
See previous.
7.
Neutral Buoyancy
The condition in which the forces acting on an object that is submerged in or floating on a fluid are
balanced.
8.
Archimedes’ Principle
Explains why some objects float in water while
others sink; states that the buoyant force acting on
an object equals the weight of the fluid displaced
by the object; if the force of gravity is greater than
the buoyant force, the object will sink, and vice
versa.
9.
Average Density
The total mass of all of the substances that make up an object divided by the total volume of the
object.
10.
Pressure
The force acting on a certain area of a surface.
11.
Pascal
A unit used to measure pressure; 1 Pa is equal to 1 N/m2.
12.
Compressibility
The ability of a substance to be squeezed into a smaller volume or space Incompressible.
13.
Static Pressure
Occurs when force is applied to an enclosed fluid (a fluid that is not
moving).
14.
Hydraulics
The study of pressure in liquids.
15.
Hydraulic Multiplication
The ability to increase and transmit a force through a liquid from one
point to another.
16.
Hydraulic Systems
Devices that transmit applied force through a liquid to
move something else.
17.
Pneumatic Systems
Devices in which a gas is used to
transmit force; force is exerted on
a gas in an enclosed space to
compress the gas and build up
force that can be used elsewhere.
18. Controlled Variable
A variable that is held constant (not allowed to change) during an experiment.
When conducting an experiment involving pressure and volume, temperature would have
to be controlled, by keeping it the same so as not to alter the outcomes.