The purpose of an experiment is to LEARN the EFFECT of something.
The way you do that is to CHANGE the thing and see what happens.
You can change as many things as you want to. But If you change
TWO things and observe the result, then you don't know which one
of them caused the effect you see.
Or maybe BOTH of them working together caused it. You don't know.
So your experiment is not really much good. You need to do it again.
Answer:

Explanation:
A body has acceleration when there is a change in the velocity vector, either in magnitude or direction. In this case we only have a change in magnitude. The average acceleration represents the speed variation that takes place in a given time interval.
a)

b)

Answer:
Let's start by understanding what exactly a scientific question is. A scientific question is a question that may lead to a hypothesis and help us in answering (or figuring out) the reason for some observation. A good scientific question has certain characteristics. It should have some answers (real answers), should be testable.
Here's examples of a few:
Why is that a star?
or
What is that star made of?
Hope this can lead you to the answer you're looking for at least!!