It is inertia, Isaac Newton's first law of motion, also known as the law of inertia , states that an object at rest will stay at rest and an object in motion will stay in motion with the same speed and direction unless acted upon by unbalanced force.
Most likely the students are using a crude measurement of time, like a stopwatch. They would get the best results with a scientific apparatus that uses a computer and optical sensors. Even recording their dropped objects with a video camera and analyzing the video would give more consistent results. Results will also vary greatly if different people are taking the time measures instead of one person making all measurements.
they are formed by layers of dead cells and is produced by the formation of multiple layers of suberized periderm, cortical and phloem tissue.
