Gravity Exercise

• The weight of the earth is 5.9736e+24kg (let's call it 6e+24kg).
• The radius is 6375 km or 6.375e+6m
• What force does it exert on us? (a=9.81m/s^2)
• What does this mean?
• Can you calculate how long it takes for a cannon ball to fall 30 m?
• You need calculus to get really accurate, but you can just do it with time slices. (Calculate speed after one time slice, subtract that from the height, repeat.)
• Note that this ignores wind resistance and other effects.