Answer:
57.39 rev
Explanation:
From circular motion,
s = rθ................... Equation 1
Where s = distance, r = radius, θ = angular distance.
make θ the subject of the equation
θ = s/r............... Equation 2
Where can look for s using any of the equation of motion
s = (v+u)t/2............ Equation 3
Where v and u = Final and initial velocity respectively, t= time.
Given: v = 21.5 m/s, u = 0 m/s (at rest), t = 11.4 s
Substitute into equation 3
s = (21.5+0)11.4/2
s = 122.55 m.
given: r = 66.5/2 = 33.25 cm = 0.3325 m
Substitute into equation 2
θ = 122.55/0.3325
θ = 368.57 rad
θ = (360.57×0.159155) rev
θ = 57.39 rev
Answer:
58.6886 revolutions
Explanation:
First we need to know the total distance travelled by the car, and we can do that using Torricelli formula:
V2= Vo2 + 2aDS
V = 21.5
Vo = 0
a = 21.5/11.4 = 1.886
(21.5)^2 = 2*1.886*DS
DS = 462.25/3.772 = 122.5477 m
For each revolution of the tire, the car moves the circunference of the tire, which is pi*d = 3.14*66.5 = 208.81 cm = 2.0881 m
So, to know the number of revolutions, we divide the total travel distance by the circunference of the tire:
122.5477/2.0881 = 58.6886
