Help with circular velocity question (unit conversions?)

In summary, the conversation discusses finding the orbital velocity of a satellite in circular low Mars orbit using the given values of R, M, and G. After some calculations, it is determined that the proper units for the answer should be m2/s2 and the units of km should be converted to m by multiplying by 1000. The final answer for the orbital velocity is 107661 m/s. The individual requesting help may need further explanation on how to change the values and properly perform the calculations.
  • #1
BilboBombadillo
11
1

Homework Statement


Consider a satellite in circular low Mars orbit 300km above the planetary surface.
R = 3396km
M = 6.419 x 1023kg
G = 6.674 x 10-11m3/kg/s2
Find the orbital velocity of the satellite (using the given values, I assume, as there is some inaccuracy in the real-life mass value. Consider it irrelevant).

Homework Equations


Vc2 = GM/R

The Attempt at a Solution



I understand the radius of this equation to refer to M2's (satellite) distance from the center of M1 (Mars), and so simply added the Mars radius and given orbital distance from the surface together.
To get R = 3696km
As it is given, I know the mass of Mars to be 6.419e+23 (or 6.419 x 1023) (is this how notation works?)Given my limited math ability, I'm having trouble interpreting (in the mental sense) the numerous measures at the end of the "gravitational constant". Those being: m3, kg, and s2

How do i go about plugging all this into a calculator? Do I ignore the units of measurement and treat everything as their values alone?

Multiplying the mass of Mars by the gravitational constant gave me:
4.2840406e+13, which i then divided by the radius of 3696
This gave me
11591018939.4
I then took the square root of this (on account of the given equation), which equaled:
107661.594542
This seems a bad number, considering known orbital velocities (I also don't understand this number. Would that read as 107661 km? or 10.7661 km? Even still this velocity would eject the satellite, no?)

I suspect I am faulting in the units of measurement and the misinterpretation of the scientific notation.

Somebody please help me, or otherwise professionally solve the equation with the given values, and then deconstruct your process for me.
 
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  • #2
You must pay attention to the units of the numbers and make sure that they cancel out to give the units of the desired answer. Notice that km = 1000m. Put that factor of 1000 in your calculations and your answer should be right. Also notice how all the units in numerators and denominators cancel out to leave the units m2/s2. Those are the proper units for V2
 
  • #3
Thankyou. That is what I suspected.
I think I need further explanation, however. You may underestimate my inproficiency at math. How precisely do go about doing as you've suggested? Where do I change the values?
 

1. How do I convert units for circular velocity?

To convert units for circular velocity, you can use the formula v = ωr, where v is the linear velocity, ω is the angular velocity, and r is the radius. You can then use unit conversion factors to convert the units for angular velocity and radius to the desired units.

2. What are the common units used for circular velocity?

The most commonly used units for circular velocity are meters per second (m/s) and revolutions per minute (rpm). However, depending on the application, other units such as kilometers per hour (km/h) or miles per hour (mph) may also be used.

3. How do I calculate circular velocity?

To calculate circular velocity, you can use the formula v = ωr, where v is the linear velocity, ω is the angular velocity, and r is the radius. Make sure to use consistent units for all variables in the formula.

4. What is the difference between angular velocity and linear velocity?

Angular velocity is a measure of the rate of change of angular displacement over time, while linear velocity is a measure of the rate of change of linear displacement over time. In simpler terms, angular velocity measures how fast an object is rotating, while linear velocity measures how fast an object is moving in a straight line.

5. Can I use any units for circular velocity conversion?

Yes, as long as the units are consistent and are able to be converted to the desired units. For example, you can use meters per second (m/s) and revolutions per minute (rpm) for circular velocity conversion, but you cannot use meters (m) and seconds (s) as these are units for different quantities.

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