Finding the vertical force?

  • #1

Homework Statement


Fireman weighs 100kg. He slides down a vertical pole with acceleration 3.0ms^-2.

a) Magnitude and direction of vertical force exerted by the pole on fireman?

Homework Equations


f=ma

The Attempt at a Solution


[/B]
f=ma
f=100(3.0)
f=300N vertically up.

But the answer says that it is actually 680N vertically up, and I do understand how they came to this conclusion.
Can you please explain where to go beyond this point? Or point out a mistake I may have made? Thank you.

I also replaced with acceleration with gravity, which did not work.
 

Answers and Replies

  • #2
billy_joule
Science Advisor
1,200
331
Your relevant equation is more correctly stated as:
∑F=ma

That is, the sum of all forces are equal to ma.
You found the net force from the firemans mass and acceleration, but you aren't asked for the net force, you are asked only for the force the pole exerts on the man.

What other force acts on the fireman?
What is it's magnitude? Can you use this information to solve for the poles force?
 
  • #3
haruspex
Science Advisor
Homework Helper
Insights Author
Gold Member
2020 Award
35,561
6,442
f=100(3.0)
f=300N vertically up
And yet, that acceleration is vertically down. Strange, don't you think?
 
  • Like
Likes billy_joule

Related Threads on Finding the vertical force?

  • Last Post
Replies
1
Views
3K
Replies
2
Views
6K
  • Last Post
Replies
4
Views
1K
Replies
4
Views
14K
Replies
2
Views
2K
  • Last Post
Replies
5
Views
860
Replies
8
Views
4K
Replies
8
Views
16K
Replies
21
Views
582
Top