Rocket Science 2025

What is Escape Velocity?

Escape Velocity is the speed needed to stop falling back to Earth (and it varies depending on how far into space you want to go.)

How fast do you need to be to remain in outer Earth orbit?

To remain in outer Earth orbit you need to reach at least 30, 000km/hr.

When and what was the name of the first moon landing?

Saturn V 1969.

What is a force?

The physics based definition of a force is: a push or a pull that is exerted on an object. Forces can do 3 things - 1. they can make an object change direction, 2. change velocity and or 3. change shape. They can make an object do all of these things simultaneously too!

What is a Gravity Field?

A gravitational field is a model used to explain the influence that a massive body like a planet extends into the space around itself, producing attraction force on another bodies. The further away from the planet, the less the field strength of the gravitational field (lines get farther apart).

What masses produces a gravitational field?

Any mass produces a gravitational field. (The bigger the mass the more powerful the gravitational field).

What is the gravitational field on Earth in (N/kg)?

On the Earth's surface this is 9.8 N/kg but in Year 8 we round that to 10 N/kg. (Newton/Kilograms). This means that for each kg of mass, an object will experience 9.8 N of force.

What do good rockets need to overcome (forces)?

A good rocket design needs to overcome three main forces acting against it: Inertia = the resistance force to start moving; Gravity force = the force applied by Earth's gravity field (This is why rockets need to reach escape velocity); Air resistance = friction pushing against the rocket nose and fins due to air particles striking it as it moves through the Earth's atmosphere

What are the different types of forces?

Different types of forces: Gravitational Force; Magnetic Force; Electrostatic Force; Buoyancy Force; Frictional Force (air resistance); Centripetal Force; Inertia

What are Frictional Forces?

Frictional forces are observed whenever two surfaces rub together. Frictional forces always generate some heat. Frictional forces always act opposite to the direction of motion of the object. Friction will always try to slow it down.

What is Air Resistance?

Air resistance is a type of frictional force caused when an object moves within the earth's atmosphere. Air particles strike against the leading surfaces of the object and they must be displaced (pushed aside) to enable the object to move ahead.

Why is aerodynamic design important?

Aerodynamic design reduces friction by reducing air resistance. The faster an object travels, the more critical aerodynamic design becomes because air resistance increases.

What is a aerodynamic design?

The less the air that is disturbed the more aerodynamic the shape is.

What must we account for before we make an aerodynamic design?

The density of the atmosphere and the speed at which the vehicle must travel.

What is the minimum number of fins?

3 fins is the minimum as the rocket must be stabilised in 3 dimensions - fins stabilise vertical and horizontal dimension. (third one is roll)

What is the coefficient of drag?

The lower the coefficient of drag (cD) the more aerodynamic the shape. (It helps us to compare different object's /shapes aerodynamics).

What is form drag?

Form drag is drag as a result of the shape of an object.

What is skin drag?

Skin drag is drag as a result of the surface of an object.

How do you reduce skin drag?

To reduce skin drag, make a 'smoother' object.

Why do planes that fly under sonic speeds have rounded nose cones and planes that fly over sonic speeds have pointy nose cones?

Under Sonice Speeds: Air particles at a given point move out of the way of an object flying at subsonic speeds, before it actually reaches that point. Having a round nose cone facilitates the gentle movement of air particles over and around it, while keeping frictional drag (skin drag) to a minimum. Above Sonic Speeds: Air particles exhibit very different behavior when in contact with objects traveling at transonic speeds or greater. At such speeds, air particles at any given point have little to no time to move out of the way before the object reaches them. The result is a shock wave, leading to very high pressure at the aircraft’s nose, and low pressure behind it.

What must happen for a rocket to be stable?

In order for a rocket to fly successfully it must have its centre of gravity in front of its centre of pressure.

What is the centre of pressure?

The centre of pressure is the point on a rocket or aircraft about which all the forces due to air pressure act and will try to turn the aircraft -like a pivot point.

What is the centre of mass?

The center of mass of an object or system is the point where mass is evenly distributed in all directions.

What is a contact force?

If the two objects physically touch each other then it is called a contact force.

What is a non-contact force?

If the two objects exert a force but do not physically contact each other it is considered a non-contact force.

What is Gravitational Force?

This is the force of attraction exerted between any two objects.

How fast does the attraction force of Earth's Gravity accelerate an object?

The attraction force of Earth's gravity will accelerate all objects (no matter what mass they are) at about 10 m/s/s. (an object accelerates 10 meters per second (m/s) per second).

How does gravitational force increase?

The closer two objects are to each other and the greater the mass the stronger the gravitational attraction between them! This is why we feel so much lighter on the moon (1/6th size/mass of the earth).

Why when you are free falling you feel weightless?

Because everything falls to earth at the same speed due to gravity (without other forces).

What happens to the gravitational force as you move further away?

The further you move away from an object the gravitational field become less (weaker). This is because the field liens spread out more.

What is electrostatic force?

Electrostatic force of attraction occur when two materials rub together causing electrons to be physically rubbed off one surface onto another surface.

What is magnetic force?

Unlike poles (North and South poles) will exert a force of attraction between them and like poles will exert a force of repulsion between them. Note that both types of poles will be equally attracted to iron.

What materials can be made into magnets?

Magnets are made out of materials that can form magnetic domains. Only Ferro-magnetic metals can become magnetic.

What is buoyancy force?

Buoyancy force is an upwards force that acts against an object that is put in a liquid. Buoyancy forces still act even if an object sinks! This is why a piece of concrete feels lighter under water than it does when you hold it above the water.

What is Centripetal Force?

Centripetal Force is the force that keeps objects in circular motion. It always acts towards the centre of the circle in which the object is moving. Centripetal Force does not cause the object to move, but it keeps the object in circular motion.

What is force measured in?

Force is measured in units called 'newtons' (N) (named after Isaac Newton). The force of 1 newton can be experienced when you hold 100 grams. Note! 1 kg of mass = 10 newtons of force (weight) on Earth.

What is G-force?

A G-force is the amount of force on an object compared to Earth's gravity. If we experience 2 G's then we would feel twice as heavy. 3 G's and we would feel three times heavier etc..

What is the maximum G-force that a human can withstand?

•NASA has worked out that the most well-trained and well-equipped pilot can withstand is about 18 G if they are wearing a G suit. •You can feel about 3 G in the amusement ride centrifuge or on a roller coater. •At forces over 5 G, most people will black out due to lack of blood in their brains.

What is Isaac Newton's first law of motion?

First Law - "an object will stay at rest or continue in a straight line unless acted upon by an outside force"

What is inertia?

The tendency for things to keep doing what they're doing is called inertia. (Isaac Newton's First Law)

What is Isaac Newton's third law of motion?

Third Law - "For every action there is an equal and opposite reaction" e.g When our rocket pushes the water out, the water pushes back equally on the rocket.

What is reaction propulsion?

•The “action” is when the rocket expels pressurized gases backwards (in our case water) •The “reaction” is the forward force exerted on the rocket known as propulsion or thrust. •This is called reaction propulsion.