Adevice used to open and close an electric circuit is a(n)
a. light bulb.
b. energy source.
c. switch.
d. resistor.
select the best answer from the choices provided

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.