A common device for entertaining a toddler is a jump seat that hangs from the horizontal portion of a doorframe via elastic cords (Fig, 15-63). Assume that only one cord is on each side in spite of the more realistic arrangement shown. When a child is placed in the seat, they both descend by a distance d s as the cords stretch (treat them as springs).Then the seat is pulled down an extra distance d m and released, so that the child oscillates vertically, like a block on the end of a spring. Suppose you are the safely engineer for the manufacturer of the seat. You do not want the magnitude of the child’s acceleration to exceed 0.20 g for fear of hurting the child’s neck. If d m = 10 cm, what value of d s corresponds to that acceleration magnitude? Figure 15-63 Problem 110.
A common device for entertaining a toddler is a jump seat that hangs from the horizontal portion of a doorframe via elastic cords (Fig, 15-63). Assume that only one cord is on each side in spite of the more realistic arrangement shown. When a child is placed in the seat, they both descend by a distance d s as the cords stretch (treat them as springs).Then the seat is pulled down an extra distance d m and released, so that the child oscillates vertically, like a block on the end of a spring. Suppose you are the safely engineer for the manufacturer of the seat. You do not want the magnitude of the child’s acceleration to exceed 0.20 g for fear of hurting the child’s neck. If d m = 10 cm, what value of d s corresponds to that acceleration magnitude? Figure 15-63 Problem 110.
A common device for entertaining a toddler is a jump seat that hangs from the horizontal portion of a doorframe via elastic cords (Fig, 15-63). Assume that only one cord is on each side in spite of the more realistic arrangement shown. When a child is placed in the seat, they both descend by a distance ds as the cords stretch (treat them as springs).Then the seat is pulled down an extra distance dm and released, so that the child oscillates vertically, like a block on the end of a spring. Suppose you are the safely engineer for the manufacturer of the seat. You do not want the magnitude of the child’s acceleration to exceed 0.20g for fear of hurting the child’s neck. If dm = 10 cm, what value of ds corresponds to that acceleration magnitude?
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…
Physics for Scientists and Engineers: A Strategic Approach, Vol. 1 (Chs 1-21) (4th Edition)
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