IGCSE Physics Definitions Flashcards
In order of: 1. Forces and Motion 2. Electricity 3. Waves 4. Energy and Thermal 5. Solids, Liquids and Gases 6. Electromagnetism 7. Atomic Physics 8. Astrophysics
Forces and Motion
Scalar
A quantity that has a magnitude
Vector
A quantity that has magnitude and direction
The moment (or torque) of a force
force * the perpendicular distance from the point to the line of action of the force, ie moment = F x d, UNIT: Nm
the principle of motions
for a system to be in equilibrium, sum of anticlockwise moments about a point = sum of clockwise moments about the same point
centre of gravity
the single point within a body at which the entire weight of the body is considered to act
displacement
the displacement of a point B from a point A is the shortest distance from A to B, together with the shortest distance. unit: m
average speed
average speed = total distance travelled / total time taken
instantaneous speed
rate of change of distance. unit: m/s
average velocity
average velocity = total displacement / total time taken. unit: m/s
velocity
the velocity of a body is the rate of change of displacement. unit: m/s
average acceleration
average acceleration = change in velocity / time taken. unit: m/s^2
momentum
the momentum of an object is its mass multiplied by its velocity. (p = mv). it is a vector. unit: kg m/s
mass
a measure of the amount of substance (matter) in an object
gravitational field strength (g)
the force experienced per unit mass by a mass placed in the field
weight
the force that acts upon an object due to its position in a gravitational field
resultant force
when the forces acting on an object are unbalanced, causing the object to accelerate
newton’s 1st law of motion
an object continues in a state of uniform motion in a straight line, or remains at rest, unless acted upon by a resultant force
newton’s 2nd law of motion
the rate of change of momentum of an object is proportional to the resultant force acting on it, and takes place in the direction of that force
newton’s 3rd law of motion
if an object A exerts a force on a second object B then B must exert a force which is equal in magnitude but opposite in direction on A
elastic collision
a collision in which there is no loss of kinetic energy
inelastic collision
a collision in which kinetic energy is lost
hooke’s law
the extension of an object such as a wire or spring is proportional to the stretching force, provided the extension is not too large. (F = kx)
friction
a force that acts between two surfaces that resists motion between the surfaces
terminal velocity
the terminal velocity is the constant, maximum velocity of an object when the resistive forces on it are equal and opposite to the accelerating forces (eg pull of gravity)