Solving Physics Problems: Skydiver's Acceleration at 80mph

[Neveda]

Physics help!?

Homework Statement

A skydiver has mass of 75g, traveling at 80mph, drag force on skydiver is 650N. Find acceleration of skydiver at 80mph (g=10n/kg??)

Homework Equations

Do I use a=f/m

The Attempt at a Solution

No attempt - I am really stuck!

 

[tiny-tim]

Welcome to PF!

A skydiver has mass of 75g, traveling at 80mph, drag force on skydiver is 650N. Find acceleration of skydiver at 80mph (g=10n/kg??)
Do I use a=f/m

Hi Neveda! Welcome to PF!

(do you mean 75kg?)

Yes, use F_total = ma.

What is the total force on the skydiver? ​

 

[Stonebridge]

Yes, use a=F/m
You need to find the resultant force on the diver.
There are two forces acting on him in this question.

 

[Neveda]

EEk.. I think maybe it is 75kg and the total force is 650N But I have no idea how to even begin to work something like this out :(

 

[jegues]

The total force is not 650N, that's simply the drag force.

What other forces act on the sky diver?

 

[Neveda]

Thats the only force mentioned in the question - sorry..I need to work out acceleration yes? Do I need to find other forces..? Thanks!

 

[Neveda]

Or could anyone just advise me on how I would work out/answer a question that's similar to above..? Then I can apply the knowledge to those kind of questions... :)

 

[Centurion1]

excuse me if you have already found it but you need to find the force of gravity pulling him downwards.

 

[doc.madani]

do you guys in America need to convert your speed of 80mph to SI units of m/s ?

 

[jegues]

do you guys in America need to convert your speed of 80mph to SI units of m/s ?

I guess it depends on the units in which they want the answer in. Generally,(in my experience atleast) answers tend to be in SI units.

 

[Centurion1]

we always use si in my class. its easier that way. (especially for conversion

 

[Neveda]

Ok..but how do I work out the answer for a question similar to above?! PLease can someone advise??