One unusual aspect of dark energy is
A) its pushes outward on everything in the universe instead of pulling inward as gravity ordinarily does.
B) it's made of a material that has not yet been observed in our laboratories.
C) Both of the above.
D) it exerts no gravitational force.
E) it exerts a new kind of fundamental force, never observed before.
Question 2
A 7.0-kg pipe is hung from a steel wire that is 2.5 m long and has a diameter of 0.75 mm. Young's modulus for steel is 2.0 1011 N/m2.
(a) By what distance does the wire stretch?
(b) If the wire diameter were doubled, what would be the stretch?