Why does a skateboard coasting on a flat surface slow down and eventually comes to a stop

The experiment done in lab is repeated, using a ball that has unknown mass m. you plot your data in the form of f 2 versus m/l, with f in rev/s, m in kg, and l in m. your data falls close to a straight line that has slope 3.19 m/(kg · s2). use g = 9.80 m/s2 and calculate the mass m of the ball.

Which of the following statements correctly describes a transformer?

Two point charges are separated by a certain distance. how does the strength of the electric field produced by the first charge