accelerationVelocity gained or lost in each unit of time. Speeding up, slowing down and turning are all accelerations.
displacementHow far, and which way, the end is from the start. A runner who finishes a lap where it began has covered 400 meters and has a displacement of zero.
distanceHow much ground a trip covers, turns and all. One lap of a 400-meter track is a distance of 400 meters, wherever the runner ends up.
frame of referenceThe viewpoint from which a motion is measured. A passenger sitting on a moving train is at rest in the train's frame and moving in the frame of the platform.
kinematicsThe study of how things move, not why they move. It is sometimes called the geometry of motion. The forces behind a motion belong to another branch, dynamics.
originThe zero point from which positions are measured. Where it is put is a free choice: the start line of a race is a common one.
positionWhere an object is, measured from a chosen point. On a straight track one number is enough, such as 3 meters east of the start.
Show all 36 terms (29 more)
Describing motion, continued
scalarA quantity told in full by a number and a unit. Length, mass and time are scalars. Speed is the scalar size of a velocity.
speedHow quickly distance is covered. It has a size and no direction. A car's speedometer shows the speed at that instant.
time intervalHow long passes from one clock reading to the next. It is the later clock reading minus the earlier one: from 2 seconds to 5 seconds is an interval of 3 seconds.
vectorA quantity that needs a direction to be complete. It is drawn as an arrow whose length shows the size. Displacement, velocity and acceleration are vectors.
velocityThe rate at which position changes, with direction. A car rounding a bend at a steady 30 miles an hour is changing velocity, because its direction is changing.
Rates, graphs and equations 12
area under the curveThe space between a graph line and the time axis. Under a velocity-time graph it gives the displacement: 10 meters per second kept up for 4 seconds is a rectangle worth 40 meters.
average speedA trip's length shared out over its duration. A trip of 120 miles in 2 hours has an average speed of 60 miles an hour, however the speed rose and fell on the way.
deltaThe Greek letter that stands for a change in. The capital letter is a triangle. Delta v is the final velocity minus the initial velocity.
instantaneous velocityThe velocity at one single moment. On a position-time graph it is the slope of the curve at that moment.
jerkThe rate at which an acceleration changes. Its SI unit is the meter per second cubed. Position changes at a rate called velocity, velocity at a rate called acceleration, and acceleration at a rate called jerk.
kinematic equationsThe formulas for motion at constant acceleration. One of them is v = u + at: the final velocity is the starting velocity plus the acceleration times the time. They are often called the SUVAT equations.
meter per second squaredThe unit in which SI measures acceleration. An object accelerating at 1 meter per second squared gains 1 meter per second of velocity every second.
position-time graphA plot of where an object is at each moment. Its slope is the velocity. A flat line means the object is standing still.
slopeRise divided by run between two points of a line. A line that climbs 20 meters while 4 seconds pass has a slope of 5 meters per second.
uniform accelerationA velocity change of the same amount each second. A ball falling with no air resistance is the usual example: its velocity grows by the same amount in every second of the fall.
uniform motionTravel along a straight path at an unchanging speed. The velocity is constant and the acceleration is zero.
velocity-time graphA plot of how fast an object goes at each moment. Its slope is the acceleration.
Free fall and projectiles 12
acceleration due to gravityThe speed gained each second in free fall. Near Earth's surface it is about 9.8 meters per second squared, and its symbol is g.
free fallFalling with nothing but gravity acting. On the Moon in 1971 an astronaut let go of a hammer and a feather together. With no air to slow the feather, they fell at the same rate.
horizontal componentThe part of a velocity that points along the ground. For a projectile it stays the same all through the flight, since gravity pulls only downward.
initial velocityThe velocity an object has when the clock starts. It is zero for an object let go from rest. In the equations it is written u, and the final velocity v.
launch angleThe tilt above level at which a projectile sets off. A launch angle of 90 degrees sends a projectile straight up, and it comes straight back down.
maximum heightThe top of a projectile's path. There the vertical velocity is zero for an instant.
parabolaA mirror-symmetric curve with one turning point. It is roughly U-shaped. Galileo showed that a projectile's path has this shape.
projectileAn object in flight with no engine, only gravity. A kicked ball and a thrown stone are projectiles once they leave the foot or the hand.
rangeHow far along the ground a projectile lands. On level ground with no air resistance, a launch at 45 degrees gives the greatest range for a given speed.
terminal velocityThe steady speed reached when drag balances weight. A skydiver speeds up until air resistance grows as large as the weight. From then on the forces are balanced and the speed stays the same.
time of flightHow long a projectile stays in the air. It is set by the vertical motion alone, which is worked out separately from the horizontal motion.
vertical componentThe part of a velocity that points up or down. Gravity changes it at a steady rate all through the flight.
How this list was compiled: Term list chosen for this site on 2026-10-12. Each meaning is written in our own words and was checked that day against the article on the term in the English Wikipedia (https://en.wikipedia.org/), whose text is under the Creative Commons Attribution-ShareAlike license: Kinematics, Dynamics (mechanics), Position (geometry), Distance, Speed, Velocity, Acceleration, Euclidean vector, Scalar (physics), Frame of reference, Origin (mathematics), Linear motion, Motion graphs and derivatives, Slope, Equations of motion, Jerk (physics), Delta (letter), Metre per second squared, Free fall, Gravity of Earth, Apollo 15, Projectile, Trajectory, Parabola and Speedometer; displacement, time interval, launch angle and time of flight against their entries in the English Wiktionary (https://en.wiktionary.org/). The projectile terms (range, the horizontal and vertical components, time of flight, maximum height), the graphs of motion and terminal velocity were checked against BBC Bitesize (https://www.bbc.co.uk/bitesize/guides/zrsdmp3/revision/1 and its next two pages, Projectile motion; https://www.bbc.co.uk/bitesize/guides/zxrtw6f/revision/1 and its next page, Velocity-time graphs; https://www.bbc.co.uk/bitesize/guides/z2x9v9q/revision/1, Motion; https://www.bbc.co.uk/bitesize/articles/zrqx2v4, Terminal velocity) and against the Beginner's Guide to Aeronautics of the NASA Glenn Research Center (https://www1.grc.nasa.gov/beginners-guide-to-aeronautics/free-fall-without-air-resistance/, .../termvel/, .../ballistic-flight-equations/ and https://www.grc.nasa.gov/www/k-12/airplane/vectors.html, Scalars and Vectors). The fact after each meaning is from the same pages. The worked figures (the lap of a track, 120 miles in 2 hours, the slope of 5 and the rectangle of 40 meters) are our own arithmetic. Licence: own work
How it works
This kinematics vocabulary worksheet lists position, distance, displacement, speed, velocity, acceleration, vector, scalar and four more terms down the left, with their meanings mixed up down the right, and prints its answer key last.
Read the full guide
Rates, graphs and equations
Set opens on Describing motion. The second set has average speed, instantaneous velocity, uniform motion, uniform acceleration, position-time graph, velocity-time graph, slope, area under the curve, kinematic equations, jerk, delta and meter per second squared.
Free fall and projectiles
The third set has free fall, acceleration due to gravity, projectile, initial velocity, parabola, range, launch angle, horizontal component, vertical component, time of flight, maximum height and terminal velocity.
Force, friction and inertia are on the force and motion word search: kinematics describes a motion without asking what causes it.
Questions and answers
What is the difference between kinematics and dynamics?
Kinematics describes how an object moves: its position, its velocity and its acceleration. Dynamics asks why it moves that way, and brings in the forces that act on it.
What are the kinematic equations?
They link five quantities of a motion at constant acceleration: displacement s, starting velocity u, final velocity v, acceleration a and time t. Three of them are v = u + at, s = ut + (1/2)at^2 and v^2 = u^2 + 2as.
What are the units of velocity and acceleration?
Velocity is measured in meters per second and acceleration in meters per second squared. Each needs a direction as well as a number, because both are vectors.