# Homework Help: Weight of astronat onshuttle

1. Nov 24, 2007

### izforgoat

1. The problem statement, all variables and given/known data

If ashuttle has a centripedal accelerationof .54m/s2, what is the weight of a 50kg astronat in that shuttle?

other info I don't know if I need.
T= 5400sec
r=400,000m
2. Relevant equations

fnet = ma

I don't know if I am supposed to use $$\varpi$$= mg + ma but I don't think so

3. The attempt at a solution

so basically I'm just verifying if I should do f = ma and that will give me the weightofthe astronatu? thanks.

2. Nov 24, 2007

### Shooting Star

By weight, is it meant the force with which the earth is pulling the astronaut, or his/her weight relative to the shuttle? Do one thing, find both.

When we are standing or sitting on the earth's surface, then we exert a force on the ground and the ground exerts a force back on us, which prevents us from going through the ground toward the centre of the earth. This we perceive as weight.

3. Nov 24, 2007

### D H

Staff Emeritus
izforgoat, is that the exact phrasing of the question, or your interpretation? The phrasing "If a shuttle has a centripedal acceleration of .54m/s2" seems a bit odd.

The astronaut's "actual weight" is by definition the gravity force on the astronaut. The astronaut's "apparent weight" is what the astronaut feels. "Apparent weight" is the sum of all forces acting on an object but gravity. Gravity cannot be felt. (You don't feel gravity acting on you right now. You feel the chair you are sitting on pushing up on you with a force equal in magnitude to the gravitational force acting on you.)

4. Nov 24, 2007

### izforgoat

exact wording

perhaps this is incorrectly phrased but the actual question is

thespace shuttle is in orbit at400km above the earth's surfce, and rounds the earth every90 minutes.

b) what is the weight of a 50kg person in the spaceshuttl?

so I knew I had to havecentripedal acceleration. I'm thinking I'm looking for apparent weight no?

5. Nov 24, 2007

### D H

Staff Emeritus
No. I would say you are looking for actual weight. BTW, the astronaut's apparent weight has nothing to do with the orbital period unless the Shuttle happens to rotating about its center of mass at the orbital rate.

6. Nov 24, 2007

### izforgoat

so... in conclusion

so it would be f = m * centripedal acceleration?

7. Nov 24, 2007

### Shooting Star

The apparent weight is zero, as the astronaut shares the motion of the shuttle. Actual weight would be mass*centripetal accn.

8. Nov 24, 2007

### izforgoat

Thanks a lot

If you guys could check out the tetherba|| question I posted before this. That's the one i'm having the most problems with out of the whole set.