Answer:
For a plant cell: The cell wall and the cell membrane
For animal cells: Just the cell membrane
Use the conservation of angular momentum; angular momentum at the beginning = angular momentum at the end
Conservation of angular momentum:
I1 w1 = I2 w2
Where I is the moment of inertia. For a sphere, I=2/5 m R^2. Substituting into the equation above we get
w2 = I1 w1 / I2 = w1 m1 R1^2 / (m2 R2^2)
w2 = w1 4 * (R1/R2)^2
= 4*(1)*(7E5/7.5)^2
= 3.48E10 revs/(17days)
= 2.04705882 x 10^9 revs/sec
Hydrogen makes stars and stars spend most of their lifetime making helium.
The heavier elements are made when an old-age, high mass star explodes as a nova or supernova and then dies.
Lead filled. it has a higher mass, therefore gravity pulls on it harder, in turn making it fall faster. think of the saying "the bigger they fall, the harder they fall", in this case its "faster", not "harder."
