# When an elevator moves upwards with an acceleration

1. Oct 10, 2011

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

When an elevator moves upwards with an acceleration, what is the equation for tension?

Is it T+W =ma?

When an elevator moves downwards with an acceleration, would the equation be

T+W=-ma?

Thats all. Thanks.

I really can't figure it out. All I know is that the equations T-mg=ma (for upwards) and T-mg=-ma (downwards) are wrong.

2. Relevant equations

3. The attempt at a solution

2. Oct 10, 2011

### SammyS

Staff Emeritus
Re: Tension

Draw a Free Body Diagram for each case. Use Fnet=ma .

3. Oct 10, 2011

Re: Tension

N = mg + ma if the elevator has an upward acceleration
N = mg - ma if the elevator has a downward acceleration

Would tension be the same as normal force in this situation?

4. Oct 10, 2011

### SammyS

Staff Emeritus
Re: Tension

For this problem, what is the normal force being used for?

Draw a Free Body Diagram for each case. Use Fnet=ma .

5. Oct 10, 2011