According to Einstein's theory of relativity, the universe is made of
A) matter and anti-matter.
B) radiation.
C) energy.
D) popcorn.
E) matter.
Question 2
A 3.0-kg and a 5.0-kg box rest side-by-side on a smooth, level floor. A horizontal force of 32 N is exerted on the 5.0-kg box pushing it against the 3.0-kg box, and, as a result, both boxes slide along the floor.
How hard do the two boxes push against each other? A) 12 N
B) 20 N
C) 24 N
D) 32 N
E) 0 N