Chapter 8: Force Flashcards
Gravity
The force of attraction that exists between any two bodies in the universe that have mass. The gravity at the Earth’s surface is the pull on objects near its surface towards the centre of the Earth
Contact force
The force that acts only between objects that are touching.
Non- contact force
The forces that acts between objects even though the objects are not touching.
Magnetic forces
The force (a push or pull) that acts between magnets (including earth) and magnetic objects.
Electrostatic forces
A non-contact force of electric charges at rest. We experience electrostatic forces when we pull off a jumper and our hair stands on end.
Force
(noun) a push, pull or twist. Forces are measured in newtons (N). (verb) to push, pull or twist.
Temporary Magnet
A magnet that stays magnetic only while it touches a permanent magnet, or one that is magnetic for a very short time
Permanent Magnet
A magnet that retains its magnetic effect for many years
Atom
A very small particle that makes up all things. Atoms have the same properties as the objects they make up
negative electric charge
The charge on an atom or object with more electrons than protons
Positive Electric Charged
The charge on an atom or object with fewer electrons than protons
Protons
Tiny, but heavy, particle found in the nucleus of an atom. Protons have a positive electrical charge
Newtons
A unit of measuring force.
Electrons
Very light, negatively charged particles inside an atom. Electrons move around the central nucleus of an atom
Insulators
Materials that do not allow electric charge to flow through them
Conductors
Materials that allow electric charge to flow through them
Weight
A measure of the size of the gravity force pulling an object towards the centre of a massive body, such as the Earth. The weight of an object depends on the object’s mass
Mass
A measure of the amount of material in an object of substance
Newtons
The unit for measuring forces
Terminal Speed
The constant speed reached by a falling body. A body reaches terminal speed when the force of gravity pulling it down is balanced by the air resistance pushing against it
Air Resistance
The force of air pushing on an object as the object moves through the air
Friction
A force that acts against the movement of an object. It occurs between any surfaces that are touching and trying to move past each other
Lubricants
Substance with large particles that can slide easily over each other. Lubricants are used between surfaces that rub against each other to reduce wear and increase motion between the surfaces
Traction
This type of friction, used to assist movement, is called traction.
Buoyancy
A force which keeps objects floating
Surface Tension
The ‘firmness’ of the surface of a liquid created by the attraction between particles at the surface. The surface acts like an elastic skin
