# Free-falling bodies

1. Feb 22, 2009

### darthxepher

I am having trouble on this problem.

An object of mass 10 kg is dropped from a great height. (a) If the object is subjected to air resistance equivalent to 10 times the instantaneous velocity, find the velocity. (b) How far does the object drop after 5 sec?

Ok so I thought the equation would be:

10(dv/dt) = 98-10v

but when i do the integrating factor or seperable i don't get the answer. Can someone tell me what i am doing wrong.

2. Feb 22, 2009

### HallsofIvy

Staff Emeritus
We keep getting questions like this. NO, no one can tell you what you are doing wrong because we don't know what you are doing! Please show (i) how you solved this problem, (ii) what you got as a solution, (iii) why you think that is wrong.

3. Feb 22, 2009

### darthxepher

(i) how you solved this problem,

An object of mass 10 kg is dropped from a great height. (a) If the object is subjected to air resistance equivalent to 10 times the instantaneous velocity, find the velocity. (b) How far does the object drop after 5 sec?

(ii) what you got as a solution,

Don't know how to start.

(iii) why you think that is wrong.