What do we mean when we say the universe is expanding, and how does expansion lead to the idea of the big bang and our current estimate of the age of the universe?

What is the magnitude of the acceleration vector which causes a particle to move from velocity −5i−2j m/s to −6i+ 7j m/s in 8 seconds. answer in m/s.

The diagram shows four locations in the electric field of a positive point charge m. at which location is the electric potential the greatest.

Which of the following situations is impossible? a) an object has velocity directed east and acceleration directed east. b) an object has zero velocity but non-zero acceleration. c) an object has constant non-zero velocity and changing acceleration. d) an object has velocity directed east and acceleration directed west. e) an object has constant non-zero acceleration and changing velocity.