Garrett W. answered 10/17/19
Experienced High School Tutor - Physics/Math
Let's create a general problem solving strategy to help approach problems like these.
- Set up an equation using our known variables, as well as the variable we're solving for.
- Leaving the equation as variables, expand and cancel out like terms.
- When the equation has been reduced, plug in the values for the variables. Including units isn't required, but will help you verify your work and keep things cleaner.
For this problem, we need an equation with velocity, orbital radius, and mass. My mind thinks of gravity and centripetal force. An object in orbit has equivalent gravitational and centripetal force
Fg = Fc
Now let's expand the two equations, with Mj being the mass of Jupiter, Mo being the mass of the satellite, r being the orbital radius, V being the linear orbital speed, and G being the gravitational constant. The orbital radius will be equal to the height of the object plus the radius of Jupiter.
(GMJMo) / r2 = (MoV2) / r
Cancel out like terms (Mo and an r) and simplify for V, our orbital speed
(G * MJ * Mo) / r2 = (Mo * V2) / r
(G * MJ) / r = V2
V = sqrt(G * MJ / r)
Time to plug in the values.
G = 6.67*10-11 N*m2/kg2
r = (8.50 * 10 ^ 6) + (7.14 * 10 ^ 7) = 7.99 * 107 m
Mj = 1.90 * 1027 kg
V = sqrt(6.67*10-11 N*m2/kg2 * 1.90 * 1027 kg / 7.99 * 107 m)
V = 39,826
To double check, we can simplify the units. Replace N with kg*m/s2
V = m/s = sqrt[ (N*m2/kg2)*(kg)/(m) ]
V = m/s = sqrt[ (kg*m/s2) * (m2/kg2) * (kg) / (m) ]
V = m/s = sqrt[ kg2*m3 / kg2*m*s2 ]
V = m/s = sqrt[ m2 / s2 ]
V = m/s = m/s
V = 39,829 m/s
Our answer, in linear velocity, is 39,826 m/s. If we want the angular velocity, simply divide this number by the radius.
V = r * W
W = V / r
W = 39826 / 7.99 * 107
W = 0.0005 radians/second