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January 16, 2018 | Author: Anonymous | Category: , Science, Astronomy
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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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