- #1
Nivoh
- 3
- 0
I apologize in advance for my lack of knowledge of "physics english".
First off, this is high school level. :)
I'm terribly sorry if this is confusing due to my lack of understand of the subject, the metric system, and my lack of grasp for the English language as well as terminology. What is μ?
An object is moves up a flat board, the board forms an angle of 30° with the x-axis. During 0.76s, the object accelerates from 5m/s to 0. The only forces affecting the board is gravity and friction.
ƩF=ma, R=μ*N, E=0.5mv^2+mgh, W=F*s.
I initially solved this quite easily using ƩF=ma=mg*sin30°+μ*cos30°, where a=Δt/Δv.
Out of curiousity, I figured I could solve this using conservation of mechanical energy, as R is a constant force.
So I went ahead and used R=μ*N, R=E/s, where E is the mechanical energy lost due to friction. N=mg/cos30°, E=0.5mv^2-mgh, therefore μ=R/N=(0.5mv^2-mgh)*cos30°/mgs. s=1.9m, h=0.95m, g=9.81m/s^2, v=5m/s.
I seem however, to have failed, I wonder why? :)
First off, this is high school level. :)
I'm terribly sorry if this is confusing due to my lack of understand of the subject, the metric system, and my lack of grasp for the English language as well as terminology. What is μ?
Homework Statement
An object is moves up a flat board, the board forms an angle of 30° with the x-axis. During 0.76s, the object accelerates from 5m/s to 0. The only forces affecting the board is gravity and friction.
Homework Equations
ƩF=ma, R=μ*N, E=0.5mv^2+mgh, W=F*s.
The Attempt at a Solution
I initially solved this quite easily using ƩF=ma=mg*sin30°+μ*cos30°, where a=Δt/Δv.
Out of curiousity, I figured I could solve this using conservation of mechanical energy, as R is a constant force.
So I went ahead and used R=μ*N, R=E/s, where E is the mechanical energy lost due to friction. N=mg/cos30°, E=0.5mv^2-mgh, therefore μ=R/N=(0.5mv^2-mgh)*cos30°/mgs. s=1.9m, h=0.95m, g=9.81m/s^2, v=5m/s.
I seem however, to have failed, I wonder why? :)
Last edited: