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Rocket Science Dr. Martin Hendry Glasgow University Reach for the Stars
To ISS: £20 million To Elgin: £20
Isaac Newton
Isaac Newton
Galileo Galilei
How do things move?….
Aristotle’s Theory: 1. Objects move only as long as we apply a force to them 2. Falling bodies fall at a constant rate 3. Heavy bodies fall faster than light ones
How do things move?….
v Aristotle’s Theory:
Galileo’s Experiment:
1. Objects move only as long as we apply a force to them 2. Falling bodies fall at a constant rate 3. Heavy bodies fall faster than light ones
1. Objects keep moving after we stop applying a force (if no friction) 2. Falling bodies accelerate as they fall 3. Heavy bodies fall at the same rate as light ones
How do things move?….
Aristotle’s Theory:
Galileo’s Experiment:
1. Objects move only as long as we apply a force to them 2. Falling bodies fall at a constant rate 3. Heavy bodies fall faster than light ones
1. Objects keep moving after we stop applying a force (if no friction) 2. Falling bodies accelerate as they fall 3. Heavy bodies fall at the same rate as light ones
How do things move?….
v Aristotle’s Theory:
Galileo’s Experiment:
1. Objects move only as long as we apply a force to them 2. Falling bodies fall at a constant rate 3. Heavy bodies fall faster than light ones
1. Objects keep moving after we stop applying a force (if no friction) 2. Falling bodies accelerate as they fall 3. Heavy bodies fall at the same rate as light ones
Apollo 15 astronaut David Scott
How do things move?…. Newton built on Galileo’s work and proposed 3 laws of motion:
1. A body moves in a straight line unless acted on by some force
How do things move?…. Newton built on Galileo’s work and proposed 3 laws of motion:
1. A body moves in a straight line unless acted on by some force 2. The acceleration of a body is proportional to the force on it
F = ma
How do things move?…. Newton built on Galileo’s work and proposed 3 laws of motion:
1. A body moves in a straight line unless acted on by some force 2. The acceleration of a body is proportional to the force on it
F = ma 3. To every action there is an equal and opposite reaction
Law of Universal Gravitation Every object in the Universe attracts every other object with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between them
Isaac Newton: 1642 – 1727 AD The Principia: 1684 - 1686
So to get into space, we need a lot of energy, to overcome the Earth’s gravity
Gravity lets the Earth hold onto its atmosphere
Gravity lets the Earth hold onto its atmosphere
Above 30km there is no atmosphere
The Space Shuttle burns Oxygen, Just like a car engine!
Getting from A to B….. Car engine burns petrol, releases chemical energy
Getting from A to B….. Car engine burns petrol, releases chemical energy Applies a force to turn the car’s wheels – they push against the road surface
Getting from A to B….. Car engine burns petrol, releases chemical energy Applies a force to turn the car’s wheels – they push against the road surface
The car moves forward
Getting from A to B….. Car engine burns petrol, releases chemical energy Applies a force to turn the car’s wheels – they push against the road surface
The car moves forward
Getting from A to B….. Car engine burns petrol, releases chemical energy Applies a force to turn the car’s wheels – they push against the road surface
The car moves forward
Getting from A to B….. Car engine burns petrol, releases chemical energy Applies a force to turn the car’s wheels – they push against the road surface
The car moves forward
Getting from A to B….. Car engine burns petrol, releases chemical energy Applies a force to turn the car’s wheels – they push against the road surface
The car moves forward
Getting from A to B….. Car engine burns petrol, releases chemical energy Applies a force to turn the car’s wheels – they push against the road surface
The car moves forward
Getting from A to B…..
Aircraft engine burns petrol, releases chemical energy, turns turbines
Getting from A to B…..
Aircraft engine burns petrol, releases chemical energy, turns turbines
These draw air into engine, which gets compressed and heated – pushed out with great force and great speed
Getting from A to B…..
Aircraft engine burns petrol, releases chemical energy, turns turbines
These draw air into engine, which gets compressed and heated – pushed out with great force and great speed
The plane moves forward
Getting from A to B…..
Aircraft engine burns petrol, releases chemical energy, turns turbines
These draw air into engine, which gets compressed and heated – pushed out with great force and great speed
The plane moves forward
Getting from A to B…..
Aircraft engine burns petrol, releases chemical energy, turns turbines
These draw air into engine, which gets compressed and heated – pushed out with great force and great speed
The plane moves forward
Getting from A to B…..
Aircraft engine burns petrol, releases chemical energy, turns turbines
These draw air into engine, which gets compressed and heated – pushed out with great force and great speed
The plane moves forward
Getting from A to B…..
Aircraft engine burns petrol, releases chemical energy, turns turbines
These draw air into engine, which gets compressed and heated – pushed out with great force and great speed
The plane moves forward
Getting from A to B…..
Aircraft engine burns petrol, releases chemical energy, turns turbines
These draw air into engine, which gets compressed and heated – pushed out with great force and great speed
The plane moves forward
Getting from A to B…..
Aircraft engine burns petrol, releases chemical energy, turns turbines
These draw air into engine, which gets compressed and heated – pushed out with great force and great speed
The plane moves forward
Gravity lets the Earth hold onto its atmosphere
Above 30km there is no atmosphere
Gravity lets the Earth hold onto its atmosphere
There is no air to push against
Rockets move because of the Reaction Principle Rocket engines burn oxygen; exhaust gas pushed backwards at enormous speed Oxygen
N A S A
Rockets move because of the Reaction Principle Rocket engines burn oxygen; exhaust gas pushed backwards at enormous speed Newton’s 3rd Law: rocket pushed forwards
N A S A
Rockets move because of the Reaction Principle Rocket engines burn oxygen; exhaust gas pushed backwards at enormous speed Newton’s 3rd Law: rocket pushed forwards
N A S A
Rockets move because of the Reaction Principle Rocket engines burn oxygen; exhaust gas pushed backwards at enormous speed Newton’s 3rd Law: rocket pushed forwards
A S A
Rockets move because of the Reaction Principle Rocket engines burn oxygen; exhaust gas pushed backwards at enormous speed Newton’s 3rd Law: rocket pushed forwards
Rockets move because of the Reaction Principle Rocket engines burn oxygen; exhaust gas pushed backwards at enormous speed Newton’s 3rd Law: rocket pushed forwards
Rockets can operate in space
A rocket reaches orbit and no longer needs to burn any more fuel. No net force on rocket
A rocket reaches orbit and no longer needs to burn any more fuel No net force on rocket
A rocket reaches orbit and no longer needs to burn any more fuel No net force on rocket
A rocket reaches orbit and no longer needs to burn any more fuel No net force on rocket
Gravity exactly balanced by rotation force:
Weightlessness!!
Moon’s orbit
This same balance explains why the Moon orbits the Earth….. Earth
….and why planets orbit the Sun
Orbit of the Moon The gravity of the Sun and the other planets makes the Moon’s orbit appear like a giant ‘Hula Hoop’: one complete cycle takes about 18 years.
Moon’s orbit
But how does the Moon know to orbit the Earth?
Earth
Moon’s orbit
But how does the Moon know to orbit the Earth? How does gravity act at a distance across space?
Earth
Gravity in Einstein’s Universe Einstein’s theory of gravity was General Relativity, published in 1916
Albert Einstein (1879-1955) Extension of Einstein’s 1906 Special Theory of Relativity
The speed of light is:-
300,000 -1 kms
Albert Einstein (1879-1955) Extension of Einstein’s 1906 Special Theory of Relativity
Gravity in Einstein’s Universe Gravity and acceleration are equivalent Gravity is not a force acting through space and time, but the result of mass (and energy) warping spacetime itself
Einstein’s Relativity
Gravity in Einstein’s Universe “Spacetime matter how Matter tells causes space to move, and matter tells to curve or warp spacetime how to curve”
Gravity in Einstein’s Universe
v Differences between Newtonian and Einsteinian gravity are tiny, but can be detected in the Solar System – and Einstein always wins!
Hydrogen fusion – fuelling a star’s nuclear furnace H = Hydrogen He = Helium
E = mc
2
Nuclear fusion is also the energy source in hydrogen bombs. If we could control the energy release from fusion, it would make excellent rocket ‘fuel’
Nuclear fusion is also the energy source in hydrogen bombs. If we could control the energy release from fusion, it would make excellent rocket ‘fuel’
But the thrust would be insufficient to ‘lift off’ from the Earth
Nuclear fusion is also the energy source in hydrogen bombs. If we could control the energy release from fusion, it would make excellent rocket ‘fuel’
But the thrust would be insufficient to ‘lift off’ from the Earth
The ISS could be the launch pad for the fusion rockets of the future
Hydrogen fusion – fuelling a star’s nuclear furnace H = Hydrogen He = Helium
E = mc
2
Solar sailing: Using sunbeams to explore the Solar System
The stars are VERY far away. The nearest star (after the Sun) is about 40 million million km from the Earth. It takes light more than 4 years to travel this distance. If the distance from the Earth to the Sun were the width of this screen, the next nearest star would be in Rome.
Einstein’s Relativity Matter causes space to curve or warp
Gravity in Einstein’s Universe ‘Black Hole’: warps spacetime so much that even light can’t escape
Warping spacetime
Wormholes in spacetime predicted by theories of quantum gravity, but these are unimaginably tiny, and unstable. How do we fit a spaceship through a wormhole?……
Could we use
To hold open wormholes?…
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