(a) Below are possible free-body diagrams for the forces acting on the child. Ch
ID: 1880149 • Letter: #
Question
(a) Below are possible free-body diagrams for the forces acting on the child. Choose the scenario/scenarios that is/are possible for each of these free-body diagrams. (Select all that apply.)
If the child has a mass of 13.1 kg, calculate the magnitude of the force in newtons the mother exerts on the child under the following conditions.
(b) The elevator accelerates upward at 0.902 m/s2.
___________ N
Calculate the ratio of this force to the weight of the child.
force/child's weight = ________
(c) The elevator moves upward at a constant speed.
___________ N
Calculate the ratio of this force to the weight of the child.
force/child's weight = ________
(d) The upward bound elevator decelerates at 2.20 m/s2.
___________ N
Calculate the ratio of this force to the weight of the child.
Explanation / Answer
a)
for 1st diagram: elevator moves up at increasing speed & elevator moves down with decreasng speed
for 2nd diagram: elevator moves up at constant speed & elevator moves down at constant speed
for 3rd: elevator moves down with increasing speed & elevator moves up with decreasing speed
b)
F = m(g+a) = 140.56N
ratio = 1.095
c)
F = mg = 128.5N
ratio= 1
d)
F = m(g-a) = 13.1 x (9.8-2.2) = 13.1 x 7.6 = 99.56N
ratio = 0.78
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