• Support PF! Buy your school textbooks, materials and every day products Here!

Calculate the Kinetic Frictional Force

  • #1
1
0
Member warned to use the homework template for posts in the homework sections of PF.
The alarm at a fire station rings and a 71.3-kg fireman, starting from rest, slides down a pole to the floor below (a distance of 3.63 m). Just before landing, his speed is 1.42 m/s. What is the magnitude of the kinetic frictional force exerted on the fireman as he slides down the pole?

Givens:
m = 71.3 kg
d = 3.63 m
Vf = 1.42 m/s


d = Vf(t)/2
a = Vf/t
F = ma


3.63 m = 1.42 m/s (t) /2
7.26 m = 1.42 m/s (t)
t = 5.113 s

a =1.42 m/s /5.113 s
a = .278 m/s^2

F = 71.3 kg (.278 m/s^2)
F = 19.8 N

But that's not the answer
 

Answers and Replies

  • #2
cnh1995
Homework Helper
Gold Member
3,296
1,067
The alarm at a fire station rings and a 71.3-kg fireman, starting from rest, slides down a pole to the floor below (a distance of 3.63 m). Just before landing, his speed is 1.42 m/s. What is the magnitude of the kinetic frictional force exerted on the fireman as he slides down the pole?

Givens:
m = 71.3 kg
d = 3.63 m
Vf = 1.42 m/s


d = Vf(t)/2
a = Vf/t
F = ma


3.63 m = 1.42 m/s (t) /2
7.26 m = 1.42 m/s (t)
t = 5.113 s

a =1.42 m/s /5.113 s
a = .278 m/s^2

F = 71.3 kg (.278 m/s^2)
F = 19.8 N

But that's not the answer
I didn't check your calculations but the force you have calculated is the "net force" on the fireman's body. You are asked to find the frictional force.
 

Related Threads for: Calculate the Kinetic Frictional Force

Replies
2
Views
2K
Top