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Question
Answer
Who discovered that gravity actually makes all objects fall at the same rate?
Galileo Galilei
In the absence of air resistance and other external factors, what is the trajectory of an object's shape?
A parabola
Projectile motion, according to Galileo, has two separate and independant motions that superimpose each other, what are these two motions? (They are perpendicular)
Horizontal motion
Vertical motion
What calculation is used to calculate acceleration in terms of final velocity, initial velocity and time?
a=(v-u)/t
What other three equations with 'a' can you use to find values for projectile motion? The first is in terms of final velocity (v)...
v=u+at
The second is in terms of v^2 (final velocity squared)... and r=displacement
v^2=u^2+2ar
The last is in terms of r...
r=ut+1/2at^2
If friction and other external forces didn't exist, when would an onject cease its horizontal motion?
Never
Therefore, when using the above equations for horizontal trajectory only, what single term does u (initial velocity) equal?
v
a=9.8m/s^2 ____ (because it is a vector).
down
Who theorised that if an object was thrown fast enough it would go into a permanent orbit?
Isaac Newton
What is the name for the velocity required to escape a planet's gravitational field?
Escape Velocity
The equation: Escape velocity = 2Gm(planet)/r(planet) is wrong. What is the right hand side missing?
Square root
What force provides the gradual upward lift needed for a rocket to launch?
Thrust
Along with the fuel, what must a rocket store for the engines to work?
Oxygen supply
Question
Answer
What are the two most used states of propellant?
Liquid
Solid
Which of Newton's Law's of Motion explain why a force of propelled gases downward force the rocket upwards?
The third law
The force of thrust must be greater than what other force before a rocket can lift off.
Weight
Although upwards thrust is constant, the acceleration of the rocket is never 100% and never constant either. What mass is decreasing which causes this to happen?
The fuel's mass is burning away
Since gravity also decreases as the rocket rises, what is the overall effect over time on the rocket's acceleration during its full launch?
It increases
What kind of increase does the velocity have?
Logarithmic
g forces are calculated using a division equation, normal true weight is the denominator. What is the numerator?
Apparent weight
How do you calulate apparent weight?
mg+ma
When dividing this equation by true weight, ma, the mass values cancel out leaving what equation?
(g+a)/g
Using simple maths, if an object is rising, its g force value will always be greater than what?
One
What direction would the object travel if the value of g forces was below this number?
Downwards
When in free-fall, what is the value of g forces experienced?
Zero
What types of rockets avoid excessive peaks in g forces?
Multi-stage rockets
The direction of what can be exploited to gain a boost in velocity when trying to reach orbit?