Working with my friend right now, we got stuck if anyone can help.

Significant figures are digits read directly from the measuring instrument plus one more digit, which is __ by the observer.

Which of the following units is not an official si unit

The famous scientist galileo galilei did several experiments with sloping planes, which he rolled metal balls down so that he could study motion. by changing the slope, he could study how the speed at which the ball rolled was affected. what was the independent variable in galileo's experiment? a. the speed of the ball b. the slope of the plane c. whether the ball moved d. what the ball was made of