Please help with this gravity problem (1 Viewer)

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I really have no idea where to start or how to even do this...

(a) What is the apparent weight of a 78-kg astronaut 5200 km from the center of the Earth's Moon in a space vehicle moving at constant velocity?
(b) is this towards or away from the moon?
(c) What is the magnitude of the apparent weight of a 78 kg astronaut 5200 km from the center of the Earth's Moon in a space vehicle accelerating toward the moon at 3.2 m/s^2?
(d) is this towards or away from the moon?
 

tiny-tim

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(a) What is the apparent weight of a 78-kg astronaut 5200 km from the center of the Earth's Moon in a space vehicle moving at constant velocity?
(b) is this towards or away from the moon?
(c) What is the magnitude of the apparent weight of a 78 kg astronaut 5200 km from the center of the Earth's Moon in a space vehicle accelerating toward the moon at 3.2 m/s^2?
(d) is this towards or away from the moon?
Hi jfahlgr1! Welcome to PF! :smile:

I don't really understand question (a) … is that the whole question? :confused:

Let's go straight to question (c) …

the apparent weight is the force exerted by the astronaut's feet and the spaceship on each other …

calculate it using Newton's second law of motion, and the law of gravitational force. :smile:
 
First of all you have to know the mass of the Moon first before getting the weight of the astronaut. You use this formula to find Fg:

Fg = [tex]\frac{GM}{r^2}[/tex]

where:
G = gravitational constant (6.67 * 10-11)
M = Mass of the Moon
r = 5,200,000 meters (5200 km)

After you get Fg then you mutiply it from the mass of the astronaut to get its weight.

The direction in question D is is towards the moon because you already said that the vehicle is accelerating towards the moon at 3.2 m/s2.
 

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