The orbit of a planet around the sun is a(n)

a. ellipse
b. straight line
c. circle
d. parabola

which of the following explain why the planets remain in motion around the sun?
a. density
b. gravity
c. inertia
d. both gravity and inertia

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.