Solving Physics Problems: Skydiver's Acceleration at 80mph

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Homework Help Overview

The problem involves a skydiver with a mass of 75g traveling at 80mph, experiencing a drag force of 650N. The objective is to find the acceleration of the skydiver at this speed, with some participants questioning the value of gravitational acceleration.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the application of Newton's second law, questioning whether to use the formula a=f/m and identifying the need to consider the total force acting on the skydiver. There is uncertainty about the mass value and whether additional forces, such as gravity, should be included in the calculations.

Discussion Status

The discussion is ongoing, with participants providing guidance on identifying forces acting on the skydiver and emphasizing the importance of calculating the resultant force. There is no explicit consensus on the mass of the skydiver or the total forces involved, and multiple interpretations are being explored.

Contextual Notes

Some participants note the potential need to convert the speed from mph to SI units, highlighting a common practice in their experiences. There is also a mention of the ambiguity regarding the mass of the skydiver, with suggestions that it might be 75kg instead of 75g.

Neveda
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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!
 
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Neveda said:
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! :wink:

(do you mean 75kg?)

Yes, use Ftotal = ma.

What is the total force on the skydiver? :smile:
 


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.
 


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 :(
 


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

What other forces act on the sky diver?
 


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


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... :)
 


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


do you guys in America need to convert your speed of 80mph to SI units of m/s ?
 
  • #10


doc.madani said:
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.
 
  • #11


we always use si in my class. its easier that way. (especially for conversion
 
  • #12


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

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