Given U = GMeMo/r
Where Me = mass of earth
Mo = mass of object
A spacecraft goes a distance 3R(earth) from the surface of the earth where it stops, and allows itself to drop back onto the earth from that altitude. When it strikes the earth, the potential energy is:
A. zero
B. -GMeMo/R
C. mgRe
D. infinity
Answer: B.
I want to make sure I am reasoning through this correctly and did not just luck out. Because I suck with gravitational stuff.
The reason it is not zero is because the gravitational potential energy is 0 only when the craft is at the center of the mass, which is impossible. Therefore, things at the surface of any planet have gravitational potential energy and 0 G.P.E is impossible. Because you can't go inside the core of a planet.
Yes?
Where Me = mass of earth
Mo = mass of object
A spacecraft goes a distance 3R(earth) from the surface of the earth where it stops, and allows itself to drop back onto the earth from that altitude. When it strikes the earth, the potential energy is:
A. zero
B. -GMeMo/R
C. mgRe
D. infinity
Answer: B.
I want to make sure I am reasoning through this correctly and did not just luck out. Because I suck with gravitational stuff.
The reason it is not zero is because the gravitational potential energy is 0 only when the craft is at the center of the mass, which is impossible. Therefore, things at the surface of any planet have gravitational potential energy and 0 G.P.E is impossible. Because you can't go inside the core of a planet.
Yes?