 #1
albertus50
 24
 4
 Homework Statement:

Hello everyone! i recently got an exercise that i have been struggling to complete.
Here it is: An astronaut weighing 74kg /163 pounds is in his space shuttle, 3106.856 miles / 5000kms from the center of an unknown planet. He proceeds to weigh himself with a scale, and he weighs 15kgs / 33 pounds. From his shuttle, he sees the planet at an angle of 54 degrees.
A) what is the radius of the planet?
b) what is the weight of the planet?
c) How much is the force of gravity at its surface?
 Relevant Equations:
 I think that the equation i need to use is newton's law of gravitation ( F =Gx(Mm/r^2)). and trigonometry for the 1st. However, you can use any equation as long as it solves the problem and i will do the necessary work to understand it :)
I do not know how to do this because in order to find the force of gravity it seemed to me i need to know the mass of the planet and vice versa, and for the 1st exercice i do not know whether the planet fills the astronaut's field of view. If it does in understand that i need to use trigonometry to find the radius, using 54 degrees as the angle between the xaxis (the astronaut looking perpendicularly at the center of the planet) and the top of the planet.
Thank you in advance for your answers!
Thank you in advance for your answers!