accelerate: to increase the speed of an object’s movement.
action force: the force created by one object that acts upon another.
aerodynamic: having a shape that reduces the amount of drag created by air passing around or over it.
aeronautical engineer: a person who designs and tests aircraft.
air resistance: the force that acts on an object as it travels through the air.
altitude: the height of an object above sea level.
angle: the space between two lines that start from the same point, measured in degrees.
angular momentum: an object’s resistance to either start or stop spinning due to inertia.
antenna: a metal rod that sends and receives radio waves. Plural is antennae.
artificial satellite: a man-made object that orbits the earth, moon, or other object.
astronomy: the study of the sun, moon, stars, planets, and space.
atlatl: a spear-thrower.
atmosphere: the mixture of gases surrounding Earth.
axis: an imaginary line down the middle of a sphere around which it rotates.
ballista: a large crossbow for firing a spear.
ballistic missile: a missile that is at first powered and guided but is then pulled by gravity to its target.
ballistics: the science that studies the movement of objects that are shot through the air.
ballistic trajectory: the trajectory of an object acted upon by only gravity and air resistance.
barrel: the straight shooting tube of a gun.
BCE: put after a date, BCE stands for Before Common Era and counts down to zero. CE stands for Common Era and counts up from zero. These non-religious terms correspond to BC and AD. This book was printed in 2018 CE.
biological warfare: the use of toxins or other biological matter as weapons.
booster: a rocket used to give another craft the power needed for takeoff.
bullet: the projectile used in guns.
buoyancy: the force that makes something able to float, either in the air or in the water.
calculus: a branch of mathematics involving calculations.
catapult: a large war machine used to hurl objects at an enemy.
chemical potential energy: energy that results from a chemical reaction.
combustion: a chemical reaction that produces heat and light.
combustion chamber: the part of a rocket where liquid fuel and oxidizer are combined to create a chemical reaction.
compound bow: a bow that uses a levering system, often cables and pulleys, to bend the limbs.
concentration camps: large camps where Jews and members of other groups were imprisoned by the Nazis during World War II. Prisoners were forced to perform hard labor and millions were killed.
contact force: a force that occurs when two objects are touching each other.
controversial: likely to cause the public to disagree and argue over something.
counterweight: a weight that balances another weight.
crossbow: a weapon used to shoot arrows.
culture: the beliefs and way of life of a group of people, which can include religion, language, art, clothing, food, holidays, tools, and more.
decelerate: to decrease the speed of an object’s movement.
deduction: a conclusion reached by reasoning or evidence.
drag: the force air exerts on a body moving through it.
ellipse: an oval shape.
energy: the ability or power to do things, to work.
engineer: a person who uses math, science, and creativity to solve problems or meet human needs.
escape velocity: the lowest velocity an object must have to escape the earth’s gravitational pull.
exhaust: the hot gases produced from a rocket’s engine.
fire lance: a very early gunpowder weapon.
fletching: featherlike material at the end of an arrow.
foe: an enemy.
force: a push or pull applied to an object.
fortification: a walled-in area to protect against an enemy.
free fall: when gravity is the only force acting on a moving object.
friction: a force that resists motion.
fulcrum: the point on which a lever rests or is supported and on which it pivots.
gravitational potential energy: the energy an object possesses because of its position in a gravitational field.
gravity: the force that pulls objects toward each other, and holds you on Earth.
gyroscope: a spinning wheel or disk used to measure or maintain orientation.
gyroscopic stabilization: when a spinning object stays pointed in the direction it was thrown.
horizontal: straight across from side to side.
hydrogen: a colorless, odorless, and flammable gas that is lighter than air.
independent: not influenced or affected by other things.
inertia: the resistance of an object to a change in its motion.
inversely: when something increases in relation to a decrease in another thing or vice versa.
jettison: to throw something away.
kinetic energy: energy associated with motion.
knuckleball: a baseball thrown with as little spin as possible.
lance: a long, straight wooden spear.
liquid-fueled rocket: a rocket that uses liquid propellants to create thrust.
liquid oxygen: a liquid produced by compressing oxygen gas.
lofted: an object that is propelled up.
longbow: a wooden bow drawn by hand.
machine: a device that transmits a force or motion.
Magnus effect: when air pressure on one side of a ball is greater than on the other side, making the ball move toward the side where there is less pressure.
mangonel: a military device for throwing stones and other projectiles.
marksman: a person aiming and shooting a weapon.
mass: a measure of the amount of matter in an object.
maximum height: when gravity slows the vertical velocity of a projectile to zero so it is neither rising nor falling.
maximum range: the greatest distance a projectile travels horizontally.
mechanical advantage: the amount a machine multiplies a force to make a task easier.
mechanical energy: energy that uses physical parts you can see, such as the parts of a machine. It is related to motion and height.
mechanics: the working parts of something.
Middle Ages: the period of European history after the fall of the Roman Empire, from about 350 to 1450 CE.
missile: an object or weapon that is propelled toward a target.
momentum: the force that a moving object has in the direction that it is moving.
natural state: according to Aristotle, the way an object behaves when nothing is acting on it.
normal force: the support force pushing upward on an object from the ground.
optical illusion: a trick of the eyes that makes people see something differently than it really is.
orbit: the path of an object circling another object in space.
orientation: the direction and position of an object.
oxidizer: a substance that contains oxygen, which mixes with fuel in a rocket engine to help it burn.
parabola: an upside down, U-shaped curve that is a cross section of a cone.
parallel: two lines always the same distance apart.
payload: the object or load that is being delivered by the catapult.
perpendicular: a line at an angle of 90 degrees to another line or surface. The two lines form a corner, called a right angle.
physicist: a scientist who studies physical forces, including matter, energy, and motion, and how these forces interact with each other.
physics: the study of physical forces, including matter, energy, and motion, and how these forces interact with each other.
potential energy: energy that is stored.
prehistoric: having to do with ancient times, before written human records.
prey: an animal caught or hunted for food.
probe: a spaceship or other device used to explore outer space.
projectile: an object that is thrown or launched and does not move by its own power.
projectile motion: the path that a projectile takes as it travels.
projectile science: the study of how projectiles move.
propellant: a combination of fuel and oxidizer that burns to produce thrust in a rocket.
propel: to drive or move forward.
proportional: corresponding in size.
prototype: a model of something that allows engineers to test their idea.
pulley: a simple machine consisting of a wheel with a grooved rim that a rope or chain is pulled through to help lift a load.
radiation: energy transmitted in the form of rays, waves, or particles from a source, such as the sun.
range: the distance a projectile travels horizontally.
rate: the speed of something measured in an amount of time, such as miles per hour or feet per second.
ratio: the relationship in size or quantity between two things.
reaction force: the force acting in the opposite direction to the action force.
recoil: to spring back suddenly as the result of an action force.
recurve bow: a bow with limbs that curve away from the archer when unstrung.
retro-rocket: a rocket that is fired opposite the direction of motion to slow a spacecraft down.
siege: surrounding and attacking a fortified place, such as a fort, and cutting it off from help and supplies.
siege engine: a machine built to help forces break through walls—or go over them.
solar system: the collection of eight planets and their moons in orbit around the sun, together with smaller bodies in the form of asteroids, meteoroids, comets, and dwarf planets.
solid-fueled rocket: a rocket that uses solid propellants.
Soviet Union: a country that existed from 1922 until 1991. Russia was part of the Soviet Union.
spear: a weapon with a long shaft and pointed tip, used for thrusting or throwing.
spear-thrower: a stick that makes it possible to throw spears farther and faster.
spiral: winding in a continuous and gradually widening or tightening curve.
stage: a smaller rocket that is stacked with other rockets and detaches when its fuel is used up.
streamlined: designed with a smooth surface that minimizes resistance through air or water
surface area: a measure of the total area that the surface of an object occupies.
taut: stretched tightly.
tension: a pulling force that pulls or stretches an object.
terminal velocity: the fastest an object will travel in free fall.
throttle: to control the amount of thrust.
thrust: a force that pushes an object forward.
torsion: a twisting force that turns or twirls a material.
trajectory: the curve a body travels along in its path through space.
trebuchet: a large, catapultlike structure with a moveable arm that launched damaging items into or over castle walls.
tundra: a treeless Arctic region that is permanently frozen below the top layer of soil.
turbulent: unsteady or violent movement.
variable: a symbol that holds the place for information that may change.
velocity: a measure of an object’s speed and direction.
vertical: straight up and down.
warhead: a weapon that is the explosive part of a missile.
wary: suspicious.
work: a force that moves an object a distance.
Use this chart to find the metric equivalents to the English measurements in this book. If you need to know a half measurement, divide by two. If you need to know twice the measurement, multiply by two. How do you find a quarter measurement? How do you find three times the measurement?
English |
Metric |
1 inch |
2.5 centimeters |
1 foot |
30.5 centimeters |
1 yard |
0.9 meter |
1 mile |
1.6 kilometers |
1 pound |
0.5 kilogram |
1 teaspoon |
5 milliliters |
1 tablespoon |
15 milliliters |
1 cup |
237 milliliters |