11) In which state of matter has the LEAST kinetic energy?
1 answer:
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Answer:
a) w = 2.57 rad / s , b) α = 3.3 rad / s²
Explanation:
a) Let's use the conservation of mechanical energy, we will write it in two points the highest and when touching the ground
Initial. Higher
Em₀ = U = m g h
Final. Touching the ground
= K = ½ I w²
How energy is conserved
Em₀ =
mg h = ½ I w2
The moment of specific object inertia
I = m L²
We replace
m g h = ½ (mL²) w²
w² = 2g h / L²
The height of the object is the length of the bar
h = L
w = √ 2g / L
w = √ (2 9.8 / 2.97)
w = 2.57 rad / s
b) the angular acceleration can be found from Newton's second rotational law
τ = I α
W L = I α
mg L = (m L²) α
α = g / L
α = 9.8 / 2.97
α = 3.3 rad / s²
Answer:
Δy = 7.1 cm
Explanation:
The center of mass of a body is defined
= 1 /M ∑
i
Where M is the total mass of the body, m mass of each part and ‘y’ height
Let's apply this equation to our case
We locate the reference system on the shoulders
The height of the arms is at its midpoint
y = -75/2 = 37.5 cm
With arms down
= 1/70 (63 y₀ - 3.5 37.5 - 3.5 37.5)
= 1/70 (63 y)₀ - 7 37.5)
With arms up
’= 1/70 (63 y₀ + 3.5 y + 3.5 y)
’= 1/70 (63y₀ + 7 35.5)
let's subtract the two equations
’ -
= 1/70 2 (7 35.5)
Δy = ’ -
= 2 7 35.5 / 70
ΔY = 7.1 cm