the size of each ball the thickness of the ramp the length of the ramp the time it takes the ball to travel
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: A student plans an investigation to calculate the speeds of different balls as they roll down a ramp. Which piece of information is least necessary for the student to record?
Possibilities:
- the size of each ball
- the thickness of the ramp
- the length of the ramp
- the time it takes the ball to travel

the thickness of the ramp