Answer:
A) W = 1885 J
, B) = 1885 J
, C) w = 8.68 rad / s
, D) t = 8,687 s
, E) P = 109 W F) P = 2
Explanation:
Part A The work in the rotational movement is
W = τ θ
Let's look at the rotated angle
θ = 12.0 rot (2pi rad / 1rot) = 75.398 rad
W = 25.0 75.40
W = 1885 J
Part B Let's use the relationship between work and kinetic energy
W = ΔK = Kf - Ko
As the body leaves the rest w₀ = 0 ⇒ K₀ = 0
W = -0
= 1885 J
Part C The formula for kinetic energy is
K = ½ I w²
w² = 2k / I
w = √ (2 1885/50)
w = 8.68 rad / s
Part D The power in the rotational movement
P = τ w
P = 25 8.68
P = 217 W
P = W / t
t = W / P
t = 1885/217
t = 8,687 s
Part E At average power is
P = τ ( -w₀)/ 2
We look for angular velocity with kinematics
= τ ( -w₀) /
The instant power is
P = τ w
The difference is that in one case the angular velocity is instantaneous and between averages
P / = τ w / (τ (-w₀) / 2)
P / = 2 w / Δw
For this case w₀ = o
p / = 2