Answer:
1. A1, B2, C3
2. 47.1°
Explanation:
Sum of forces in the x direction:
∑Fₓ = ma
f − Fᵥᵥ = 0
f = Fᵥᵥ
Sum of forces in the y direction:
∑Fᵧ = ma
N − W = 0
N = W
Sum of moments about the base of the ladder:
∑τ = Iα
Fᵥᵥ h − W (b/2) = 0
Fᵥᵥ h = ½ W b
Fᵥᵥ (l sin θ) = ½ W (l cos θ)
l Fᵥᵥ sin θ = ½ l W cos θ
The correct set of equations is A1, B2, C3.
At the smallest angle θ, f = Nμ. Substituting into the first equation, we get:
Nμ = Fᵥᵥ
Substituting the second equation into this equation, we get:
Wμ = Fᵥᵥ
Substituting this into the third equation, we get:
l (Wμ) sin θ = ½ l W cos θ
μ sin θ = ½ cos θ
tan θ = 1 / (2μ)
θ = atan(1 / (2μ))
θ = atan(1 / (2 × 0.464))
θ ≈ 47.1°
The correct answer is
<span>B. if Earth rotated on an axis that was not tilted with respect to Earth's orbit
In fact, the fact that Earth's axis is tilted is the reason why the durations of day and night are different in every part of the Earth. If the axis was not tilted, we would have exactly 12 hours of day and night in every point of the Earth, for the whole year.</span>
centrifugal force is a fictitious force. What is happening is that since the earth itself is not a rigid body it will deform when under motion. Although gravity attempts to make the earth spherical, as it is rotating the earth deforms, in such away that it flattens to become an oblique spheroid. This happens as the material at the equator must have a net resultant centripetal force (not centrifugal) which causes its position of equilibrium from the center of the earth to be further away than at the poles as they do not have this force as they are not rotating around the center of mass.
Answer:
Shadows are made by blocking light. Light rays travel from a source in straight lines. If an opaque (solid) object gets in the way, it stops light rays from traveling through it. The size and shape of a shadow depend on the position and size of the light source compared to the object.
Explanation:
