Space Flashcards
What is the difference between Weight and Mass?
Mass(m) is the amount of matter in an object, Weight is the force acting on an object due to a gravitational field. (W=mg)
What is Work?
Work is the product of two vectors, force and displacement (W=Fs)
What is Potential Energy?
Potential Energy the work done in moving an object an infinite distance away to a point in a gravitational field (PE = mgh)
In a linear field, what is Work equal to?
PE = W
What is “G”, in the PE formula
G is the universal gravitational constant (6.67 x10-11 Nm2Kg-2)
What is the mass of the earth?
6 x10(24) kg
What is the radius of the earth from the center?
6.37 x10(6) m
What is the acceleration due to gravity on earth?
9.8
How do vertical and horizontal components affect each other?
They DON’T influence each other. Since they are at right angles to each other
What happens if you hit an object positive horizontally and vertically in a friction less environment?
HORIZONTAL: It will not speed up or slow down VERTICAL: It will slow down due to gravity (9.8 ms-2)
What were the two things that Galileo believe about an object undergoing projectile motion?
- all objects, regardless of their mass, fell at the same rate in a friction less environment (due to gravity). 2. Perpendicular components are independent of each other (Vertical not related to Horizontal)
Explain the concept of Escape Velocity.
Escape Velocity is the Initial Velocity required by a projectile to rise vertically and JUST escape the gravitational field of the planet
What is the formula for Escape Velocity?
V[escape] = √2rg or √2GM/r
Outline Newtons concept of escape velocity
Newton created a hypothetical scenario where a person climbed up a very tall mountain and launched 3 projectiles.
- Follows a parabolic shape and hits the ground
- If the second projectile was JUST fast enough, it would travel right around the world and would not hit it
- If the 3rd one was slightly faster, it would escape earths gravitational pull
What is a “g force”
“g” force is used to express the apparent weight as a proportion of true weight . (g-force = Apparent Weight/True Weight
What is True Weight?
True Weight is the Weight of a stationary person (W=mg)
What is Apparent Weight?
What a person experiences when an external force acts on them to cause a change in motion. (True weight + Reaction on body from rocket thrust)
What can be used to give the rocket an extra boost when launching? Why would you use this?
The rotation of the earth on its axis, and the orbital motion of the earth around the sun. It allows the rocket to save fuel, while still achieving its target velocity.
How does the law of conservation of momentum affect a rocket launching?
Law of conservation of momentum is “for every action there is an equal and opposite reaction.”
The action on a rocket is the thrust of the rocket, therefore there has to be a reaction, on the gases, in the opposite direction.
How does the changing acceleration of a rocket during launch affect the forces experienced by astronauts?
Since the chair is bolted to the rocket, and the rocket has a thrust force, there has to be a reaction to that on the astronaut, who is strapped to the seat, in the opposite direction. (law of conservation of momentum)
How does a satallite orbit the earth?
The Satallite travels in a circular motion around the earth because:
- The velocity of the satallite is always directed at a tanget to the circle at every point (always point forward)
- The acceleration due to gravity is pointed towards the centre of earth.
- The Centripetal Force (mv2/r) would also be directed to the centre of the earth (centre of circle
What is the difference in approximate altitude (km) bewteen low earth orbit and geostationary orbit?
LEO: 250-1000
GO: 36000
