Fundamentals
Quantity with both magnitude and direction.
Vector Quantity
SI unit of energy.
Joule
A passenger lurches forward when a car suddenly stops because their body resists changes in motion.
Newton’s First Law (law of inertia)
The slope of a displacement–time graph represents this physical quantity.
Velocity
Heat naturally flows from a hot object to a cold one because of this relationship with temperature.
Temperature
This factor affects the period of a simple pendulum.
The lenth of the string
Law stating energy cannot be created or destroyed, only transformed.
The law of conservation of energy
A resultant force of 0 N acts on a moving object; this is the type of motion it continues in
constant velocity (uniform motion)
The area under a velocity–time graph represents this quantity.
displacement
Diffusion is fastest in this state of matter because particles have the most kinetic energy and spacing.
Gas
A runner sprints 50 m north, then 50 m south. This quantity returns to zero even though distance is not zero.
displacement
Type of collision where objects stick together.
Perfectly inelastic collision
A rocket moves upward because expelled gases produce this paired interaction force.
Newton’s Third Law (action-reaction pairs)
A body moves with constant acceleration; this type of graph is a straight line when velocity is plotted against time.
Velocity-Time Graph
A thermometer used in hospitals must respond quickly and safely to small temperature changes in the human body; this is why it is designed with a narrow range around this scale region.
Clinical temperature range (around body temperature / 35°C–42°C)
A see-saw is balanced even though forces act on both sides because clockwise and anticlockwise effects satisfy this condition.
The principle of moments (net moment = 0)
A 2 kg object moving at 3 m/s has the same momentum as a 1 kg object moving at this speed.
6 m/s
A 5 kg object and a 10 kg object are pushed with the same force. The lighter object accelerates more because this property of matter is smaller for it.
Mass (or inertia)
A car increases velocity from 2 m/s to 10 m/s in 4 s; this quantity describes the rate of change of velocity.
Acceleration
This everyday object is designed with expansion joints to prevent damage from temperature changes.
Bridges (or large structures like railway tracks)
Three forces act on a body and it remains at rest; this quantity is zero even though individual forces exist.
The resultant force
A force moves an object but no displacement occurs; in this case, this quantity is zero
The work done
Two ice skaters push off each other; one has twice the mass of the other, yet both experience forces of equal magnitude but opposite direction.
Newton’s Third Law (forces act in equal and opposite pairs on different bodies)
A displacement–time graph curves upward, becoming steeper as time increases. This indicates that the object is not moving with constant velocity but has a constant rate of change of velocity.
Uniformly accelerated motion (constant acceleration)
Overhead power lines are intentionally left loose so that changes in this property do not cause snapping or excessive tension.
length due to thermal expansion