You’re investigating ladder safety for the Consumer Product Safety Commission. Your test case is a uniform ladder of mass m leaning against a frictionless vertical wall with which it makes an angle θ . The coefficient of static friction at the floor is μ . Your job is to find an expression for the maximum mass of a person who can climb to the top of the ladder without its slipping. With that result, you’re to show that anyone can climb to the top if μ ≥ tan θ land but that no one can if μ < 1 2 tan θ .
You’re investigating ladder safety for the Consumer Product Safety Commission. Your test case is a uniform ladder of mass m leaning against a frictionless vertical wall with which it makes an angle θ . The coefficient of static friction at the floor is μ . Your job is to find an expression for the maximum mass of a person who can climb to the top of the ladder without its slipping. With that result, you’re to show that anyone can climb to the top if μ ≥ tan θ land but that no one can if μ < 1 2 tan θ .
You’re investigating ladder safety for the Consumer Product Safety Commission. Your test case is a uniform ladder of mass m leaning against a frictionless vertical wall with which it makes an angle θ. The coefficient of static friction at the floor is μ. Your job is to find an expression for the maximum mass of a person who can climb to the top of the ladder without its slipping. With that result, you’re to show that anyone can climb to the top if μ ≥ tan θ land but that no one can if
μ
<
1
2
tan
θ
.
Part C
Find the height yi
from which the rock was launched.
Express your answer in meters to three significant figures.
Learning Goal:
To practice Problem-Solving Strategy 4.1 for projectile motion problems.
A rock thrown with speed 12.0 m/s and launch angle 30.0 ∘ (above the horizontal) travels a horizontal distance of d = 19.0 m before hitting the ground. From what height was the rock thrown? Use the value g = 9.800 m/s2 for the free-fall acceleration.
PROBLEM-SOLVING STRATEGY 4.1 Projectile motion problems
MODEL: Is it reasonable to ignore air resistance? If so, use the projectile motion model.
VISUALIZE: Establish a coordinate system with the x-axis horizontal and the y-axis vertical. Define symbols and identify what the problem is trying to find. For a launch at angle θ, the initial velocity components are vix=v0cosθ and viy=v0sinθ.
SOLVE: The acceleration is known: ax=0 and ay=−g. Thus, the problem becomes one of…
Campbell Essential Biology with Physiology (5th Edition)
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