Weight and Mass Conversion with Constant Acceleration

Question

Hello, I'm having some issues with these homework questions and would appreciate a walkthrough of what kind of equation I'm supposed to use. Thank you in advance!

"An astronaut weighs 658 N on earth. (Include units with all answers)

1. What is his weight on planet LBO, where g=1.36 m/s²?
2. What is his weight on planet GBO, where g=24.8 m/s²?
3. What is his weight while traveling in outer space with constant velocity?
4. What is his mass while traveling in outer space with constant velocity?"

Answer 1

The intention of this exercise is make the distinction between "mass" and "weight".

(In Newtonian physics) mass is an inherent property of matter, independent of

any forces or movement.

Mass is measured in units of kg.

In contrast, the weight of a piece of matter depends on its proximity to other matter,

which causes gravitational acceleration.

If a piece of matter with mass m is subject to gravitational acceleration g, then its weight

w = mg (1)

Acceleration is measured in m/s², and therefore weight is measured in units kgm/s²,

which is abbreviated as kgm/s² = N.

In your homework the teacher uses the term "outer space".

I believe that is supposed to imply the absence of any forces.

This makes gravitational acceleration in outer space equal 0, and therefore

the weight in outer space is always zero for any amount of mass.

In contrast, the other questions depend on the mass of the astronaut.

We can determine that from his weight of 658 N on earth, where gravitational acceleration is

g = 9.81 m/s²

Using equation (1) that gives us his mass

m = w/g = 658N/(9.81m/s²) = (658/9.81)N/(m/s²) = 67(kgm/s²)/(m/s²) = 67kg

This gives you an immediate answer to the forth question, which asks about the mass.

Answers to the first two questions can be obtained by using the equation (1).