### Users Who Are Viewing This Thread (Users: 0, Guests: 1)

#### jfahlgr1

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

Homework Helper
Welcome to PF!

(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! I don't really understand question (a) … is that the whole question? 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. #### .:Endeavour:.

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 = $$\frac{GM}{r^2}$$

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.

### The Physics Forums Way

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving