And today's question.
How did Newton quantify gravity?
What we already know
Gravity is a weak force, Newton guessed (correctly) that that same force that made the apple fall from the tree kept the moon in orbit around the Earth
'Weightlessness'
- The best way to think about this is that you are just falling inside an airplane that is also falling
- So the net acceleration due to gravity is zero.
- What about your mass? Has this changed?
So when you 'weigh 50kg' is this correct, scientifically speaking?
'Weight' is a Force, measured in newtons (N)
F=ma
So 'weight' on Earth is proportional to mass, and most scales use this proportionality to give your 'mass' instead of your 'weight'
If F=ma, what is the 'a' in this formula?
a is acceleration due to gravity, given the symbol g
g=9.8 ms^{-2}
Newtons law of Universal Gravitation
Falling....
So 'g' can be different on different planets and stars - more mass, higher acceleration
Year 8 Gravity and the four forces of nature
By Gavin King
