Answer:
fr = m v₀² / 2 (x₁-x₀)
Explanation:
a) For this exercise we use Newton's second law
X axis
- fr = ma
Y Axis
N-W = 0
N=W
let's look for acceleration with expressions of kinematics
v² = v₀² - 2 a Δx
at the point where stop v = 0
a = v₀² / 2 Δx
let's replace
-fr = m (- v₀² / 2 (x₁-x₀))
fr = m v₀² / 2 (x₁-x₀)
b)they ask for the same
in this case part of rest
v₁² = 0 + 2 a Δx
a = v₁² / 2ΔX
we write Newton's second law
F - fr = m a
fr = F - ma
fr = F - m v₁² / 2Δx
There is a lot of help on the internet
VF=0
Vi=60mph
T=4.0s
you need to convert hours to seconds... so you do there is 60 minutes in an hour and there is 60 seconds in a minute so you do 60*3=180
180/4.0=45m/s^2
