Question

I have moooorrreee!!

So first off, you are skydiving. The air resistance slows u down at 7.2 m/s2 and you are 67.2 KG, but somehow, gravity is added to the problem too.

The second one is the exact same, except air resistance is 3.29 m/s2

Answer 1

[blank] m/s2 = meters per second squared, that is the acceleration

Answer 2

gravity's acceleration is 9.81 m/s^2

Answer 3

(and work needs to be shown too, not just answer)

Answer 4

@jim_thompson5910

Answer 5

YES, @jim_thompson5910

Answer 6

I am not sure of what you are looking for with the given information

it is a known fact for physics problems that gravity is 9.81 m/s^2

what are you looking for?

Answer 7

Newtons for both

Answer 8

like it is weird, like they want newtons but when I calculated it, with gravity, i did -7.2 + 9.81 and multiplied that by the weight, but that was wrong. What was wrong there?

Answer 9

well you are going down
gravity is pulling you down at [technically] -9.81
and air resistance is pushing up = +7.2

also, depending on the textbook/teacher/education system
they might want you to use 9.8 or even 10 m/s^2 for gravity

Answer 10

no my teacher wants 9.81, and so it would just be a negative of what I have?

Answer 11

hopefully ^_^"

Answer 12

I have 175.39 N right now

Answer 13

`So first off, you are skydiving. The air resistance slows u down at 7.2 m/s2 and you are 67.2 KG, but somehow, gravity is added to the problem too.`

the problem seems incomplete?

Answer 14

have no fear, jim is here

Answer 15

And it needs to be right, otherwise, i cant do a major grade project, which in turn fails me

Answer 16

Oh and @jim_thompson5910 I need to find N

Answer 17

They want the force pulling you down?

Answer 18

If you can, post a screenshot of the full problem

Answer 19

I don't, er, have the problem. Just the numbers, and the "slight" imagination my teacher has to make it more "fun" so that is all we have too.

Answer 20

So like this problem, everything seems to be up in the air. That's not good

Answer 21

Lol, yeah. And I attempted it, and it was wrong. (But idk if it was the #s, or just the sign)

Answer 22

how do you know it's wrong? are you typing this into a computer system?

Answer 23

No, during class, my teacher said it was wrong, both of them actually, and told me to do them for homework, and bring them tomorrow.

Answer 24

I see

Answer 25

It might be something as simple as the sign, or something as complex as all of the #s.

Answer 26

well if there was no air resistance, then the acceleration of gravity g = 9.8 pulls you down to earth with a force of

F = m*a
F = m*g
F = 67.2*9.8
F = 658.56 newtons

Answer 27

But there is air resistance too, so UGHUGHUHGHGUGHUGHUGHUGHUGHUHGUHU

Answer 28

`The air resistance slows u down at 7.2 m/s2`
this implies that the air resistance acceleration is

9.8 - 7.2 = 2.6 m/s^2

so you're being pulled down with a force of f = m*a = 67.2*7.2 = 483.84 N
the air is pushing up with a force of f = m*a = 67.2*2.6 = 174.72 N

Answer 29

if you assign down to be negative, then the force pulling you down is -483.84 N
the force pushing up is +174.72 N

Answer 30

I made a mistake! Oh goodness. But the second one?

Answer 31

so the net force is

(force pulling down) + (force pushing up) = (-483.84 N) + (174.72 N) = -309.12 N

Answer 32

which makes sense because ultimately you're going to be pulled down to earth (and not be pushed up)

Answer 33

wait I'm confused?
shouldn't you be pulled down at 67.2*9.81
and pushed up at 67.2*7.2 ?

Answer 34

That is true @jim_thompson5910

Answer 35

`shouldn't you be pulled down at 67.2*9.81`
only if there is no air resistance to slow you down

if there was no air resistance, then you accelerate towards the earth at 9.81 m/s^2

but there is air resistance slowing you down (according to the problem, it's 7.2 m/s^2)

Answer 36

mmm ok then

Answer 37

I'm back!

Answer 38

Wait @jim_thompson5910 what about the second one? is it basically #1? but with changed #s?

Answer 39

honestly I have no idea because these problems/instructions are too vague. But if you're looking for the net force (like I showed in #1), then yes you follow the same steps

Answer 40

so the a is 6.52

Answer 41

6.52 x 67.2 = 438.14

Answer 42

that would be the force pulling you down

Answer 43

I subtracted 9.81 - 3.29

Answer 44

where are you getting 3.29 ?

Answer 45

oh nvm

Answer 46

so yeah!

Answer 47

Someone help please: http://openstudy.com/study#/updates/5623f62de4b05fbf23f0a520

Answer 48

What's the problem