Physics work?

Question

An astronaut has left the International Space Station to test a new space scooter. Her partner measures the following velocity changes, each taking place in a 15 s interval. What are the magnitude, the algebraic sign, and the direction of the average acceleration in each interval described below? Assume that the positive direction is to the right.

(a) At the beginning of the interval the astronaut is moving toward the right along the x-axis at 14.0 m/s, and at the end of the interval she is moving toward the right at 4.0 m/s.
Magnitude
_______m/s and direction

(b) At the beginning she is moving toward the left at 4.0 m/s, and at the end she is moving toward the left at 15.0 m/s.
Magnitude
______m/s

(c) At the beginning she is moving toward the right at 14.0 m/s, and at the end she is moving to the left at 14.0 m/s.
Magnitude
_____m/s and direction.

Answer 1

a) v(t)=v0-a*t
since t=15
4=14+a*15
-10/15=a

b) -15=-4+a*15
a=-11/15

c) -14=14+a*15
a=-28/15

j