Review. Why is the following situation impossible? An athlete tests her hand strength by having an assistant hang weights from her belt as she hangs onto a horizontal bar with her hands. When the weights hanging on her belt have increased to 80% of her body weight, her hands can no longer support her and she drops to the floor. Frustrated at not meeting her hand-strength goal, she decides to swing on a trapeze. The trapeze consists of a bar suspended by two parallel ropes, each of length ℓ, allowing performers to swing in a vertical circular are (Fig. P8.38). The athlete holds the bar and steps off an elevated platform, starting from rest with the ropes at an angle θ i = 60.0° with respect to the vertical. As she swings several times back and forth in a circular are, she forgets her frustration related to the hand-strength test. Assume the size of the performer’s body is small compared to the length ℓ and air resistance is negligible. Figure P8.38
Review. Why is the following situation impossible? An athlete tests her hand strength by having an assistant hang weights from her belt as she hangs onto a horizontal bar with her hands. When the weights hanging on her belt have increased to 80% of her body weight, her hands can no longer support her and she drops to the floor. Frustrated at not meeting her hand-strength goal, she decides to swing on a trapeze. The trapeze consists of a bar suspended by two parallel ropes, each of length ℓ, allowing performers to swing in a vertical circular are (Fig. P8.38). The athlete holds the bar and steps off an elevated platform, starting from rest with the ropes at an angle θ i = 60.0° with respect to the vertical. As she swings several times back and forth in a circular are, she forgets her frustration related to the hand-strength test. Assume the size of the performer’s body is small compared to the length ℓ and air resistance is negligible. Figure P8.38
Solution Summary: The author explains that the force experienced by an athlete in second condition is greater than force in first condition, and the athlete's hands were not able to support it.
Review.Why is the following situation impossible? An athlete tests her hand strength by having an assistant hang weights from her belt as she hangs onto a horizontal bar with her hands. When the weights hanging on her belt have increased to 80% of her body weight, her hands can no longer support her and she drops to the floor. Frustrated at not meeting her hand-strength goal, she decides to swing on a trapeze. The trapeze consists of a bar suspended by two parallel ropes, each of length ℓ, allowing performers to swing in a vertical circular are (Fig. P8.38). The athlete holds the bar and steps off an elevated platform, starting from rest with the ropes at an angle θi = 60.0° with respect to the vertical. As she swings several times back and forth in a circular are, she forgets her frustration related to the hand-strength test. Assume the size of the performer’s body is small compared to the length ℓ and air resistance is negligible.
Example
Two charges, one with +10 μC of charge, and
another with - 7.0 μC of charge are placed in
line with each other and held at a fixed distance
of 0.45 m. Where can you put a 3rd charge of +5
μC, so that the net force on the 3rd charge is
zero?
*
Coulomb's Law Example
Three charges are positioned as seen below. Charge
1 is +2.0 μC and charge 2 is +8.0μC, and charge 3 is -
6.0MC.
What is the magnitude and the direction of the force
on charge 2 due to charges 1 and 3?
93
kq92
F
==
2
r13 = 0.090m
91
r12 = 0.12m
92
Coulomb's Constant: k = 8.99x10+9 Nm²/C²
✓
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Work and Energy - Physics 101 / AP Physics 1 Review with Dianna Cowern; Author: Physics Girl;https://www.youtube.com/watch?v=rKwK06stPS8;License: Standard YouTube License, CC-BY