Chapter 8: Forces 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
a force that acts only between objects that are touching
Non-Contact force
a force that acts between objects even though the objects are not touching
Magnetic force
the force (a push or pull) that acts between magnets (including the 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 en
Force
(noun) a push, pull or twist. Forces are measured in newtons (N). (verb) to push, pull or twist
Atoms
a very small particle that makes up all things. Atoms have the same properties as the objects they make up
Negatively charged
having a lower electric potential
Positively charged
having a higher electric potential
Protons
tiny, but heavy, particle found in the nucleus of an atom. Protons have a positive electrical charge
Neutrons
tiny, but heavy, particles found in the nucleus of an atom. Neutrons have no electrical charge
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
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
Is when the atmosphere pushes against an moving object
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
Traction
a type of friction used to assist movement
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
Buoyancy
a force which keeps objects floatin
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
