# Gravity question, HELP

1. Nov 10, 2009

### bobsagget

a 5.00 g spider is lowering itself to the floor. Its web has a tensile strength of 3.00 x 10-2N. What is the minimal accerleration with which the spider can lower itself?

So i dont know how to begin, would the tensile strength of the web be equal to the total forces? as it is equal to force of gravity and normal force? what would the steps be and how to get the answer and whats the answer? thanks a bunch!

2. Nov 10, 2009

### tiny-tim

Hi bobsagget!

Use good ol' Newton's second law to find how the tension in the web depends on the acceleration.

3. Nov 10, 2009

### bobsagget

so would the force of gravity and the normal force need to equal the total tensile strength of the web? then i can solve for acceleration after.

4. Nov 10, 2009

### tiny-tim

What normal force?

Apply Newton's second law !

5. Nov 10, 2009

### bobsagget

ok so no normal force, so how would i draw that as a fbd though? the forces are 1) force of gravity down(mg), and anything else? or would there just be on and then i have to find the acceleration if the total force applied has to be equal to that of the webs strength

6. Nov 10, 2009

### tiny-tim

Yes, the tension!!

7. Nov 10, 2009

### bobsagget

and that tension is the 3.00 x10-2

8. Nov 11, 2009

### tiny-tim

(just got up :zzz: …)

Yes, that's the critical tension (just before the web breaks), so that's the value you should use in your calculations.

What do you get?