Answer:
The tangential velocity of a rotating object is:
v = r*w
where r is the radius, and w is the angular velocity.
w = 2*pi*f
where f is the frequency.
We know that the record plater does 11 revolutions in 20 seconds, then it does:
11 rev/20s = 0.55 rev/s = f
then we have:
w = 2*pi*0.55 s^-1 = 2*3.14*0.55 s^-1 = 3.454 s^-1
The radius of a record player is really variable, it is around 10 inches, so i will use r = 10in, which is the rotating part of the record player.
then the tangential velocity is:
v = 10in*3.454 s^-1 = 34.54 in/s
The aluminum foil would reflect the most light !
When biomass is used as a fuel<span> source it is regarded as a </span>Biofuel<span>. </span>Fossil fuel<span> on the other hand take millions of years to form. They too are organic hydrocarbons, primarily coal, </span>fuel<span> oil or natural gas, formed from the remains of plants and animals.</span>
D. dull and brittle when solid
Answer:
a) α = 9.30 rad / s² and b) t = 2.26 s
Explanation:
Part A
For this exercise we will use the equation of Newton's second law rotational
Σ τ = I α
fr r = I α
Where I is the moment of inertia of the sphere
I = 2/5 M r²
We replace
fr r = 2/5 M r² α
α = 5/2 fr / M r
Let's calculate
M = 250 g (1 kg / 1000g) = 0.250 kg
r = d / 2 = 4.30 / 2
r = 2.15 cm (1m / 100cm) = 0.0215 m
α = 5/2 0.0200 / (0.250 0.0215)
α = 9.30 rad / s²
Part B
Let's use the angular kinematic equation
w = w₀ - α t
t = (w - w₀) / α
They give us the change in angular velocity 21.0 ras / s
t = 21.0 / 9.30
t = 2.26 s
