Answer:
a) α = 0.338 rad / s² b) θ = 21.9 rev
Explanation:
a) To solve this exercise we will use Newton's second law for rotational movement, that is, torque
τ = I α
fr r = I α
Now we write the translational Newton equation in the radial direction
N- F = 0
N = F
The friction force equation is
fr = μ N
fr = μ F
The moment of inertia of a saying is
I = ½ m r²
Let's replace in the torque equation
(μ F) r = (½ m r²) α
α = 2 μ F / (m r)
α = 2 0.2 24 / (86 0.33)
α = 0.338 rad / s²
b) let's use the relationship of rotational kinematics
w² = w₀² - 2 α θ
0 = w₀² - 2 α θ
θ = w₀² / 2 α
Let's reduce the angular velocity
w₀ = 92 rpm (2π rad / 1 rev) (1 min / 60s) = 9.634 rad / s
θ = 9.634 2 / (2 0.338)
θ = 137.3 rad
Let's reduce radians to revolutions
θ = 137.3 rad (1 rev / 2π rad)
θ = 21.9 rev
The force of the air resistance is 4 N.
The given parameters;
- mass of the flower pot, m = 2 kg
- weight of the flower pot, W = 20 N
Let the air resistance = F
Apply Newton's second law of motion to determine the force of the air resistance acting upward to oppose the motion of the pot falling downwards.

Thus, the force of the air resistance is 4 N.
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Answer:
The lens to be used for the objective is lens A
Explanation:
The objective of a compound microscope
The focal length of the lens used for the objective = 1/(magnification obtained)
The focal length of most modern is equal to the tube length
The range of sizes for the focal length of a microscope is between 2 mm and 40 mm
Therefore, the appropriate lens to be used for the objective of the compound is lens A that has a focal length of 0.50 cm = 5 mm