A 55 kg track and field athlete has an average power output of 5.4 kW during the 200 meter dash. How quickly did she finish the
1 answer:
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We can solve the problem by requiring the equilibrium of the forces and the equilibrium of torques.
1) Equilibrium of forces:
where
is the weight of the person
is the weight of the scaffold
Re-arranging, we can write the equation as
(1)
2) Equilibrium of torques:
where 3 m and 2 m are the distances of the forces from the center of mass of the scaffold.
Using
and replacing T1 with (1), we find
from which we find
And then, substituting T2 into (1), we find
1) Equilibrium of forces:
where
Re-arranging, we can write the equation as
2) Equilibrium of torques:
where 3 m and 2 m are the distances of the forces from the center of mass of the scaffold.
Using
from which we find
And then, substituting T2 into (1), we find
Answer:
distance from speaker is 17.87 m
Explanation:
given data
distance from loudspeaker = 2.5 m
distance between loudspeaker = 3.0 m
room temperature = 20c
wavelength f = 686Hz
to find out
what distances from the speaker
solution
we know sound velocity c = 331.5 + 0.6 × 20c = 343.5
so wavelength of sound λ = c / f
wavelength = 343.5 / 686 = 0.5 m
when the difference in distance of speaker destructive interference will be
d = λ/2 × (2n-1)
for n = 1, 2 3 4 ..
d = 0.5/2 × (2n-1)
d = 0.250 , 0.75 , 1.25 , 1.750............ for n = 1, 2 3 .............
so
for d = 0.250
side of triangle by hypotenuse of triangle are
= 0.250
0.5 x1 = 7.6875
x1 = 15.375 m
for d = 0.75
side of triangle by hypotenuse of triangle are
= 0.75
1.5 x2 = 4.6875
x2 = 3.125 m
for d = 1.250
side of triangle by hypotenuse of triangle are
= 1.250
2.5 x2 = 1.1875
x3 = 0.475 m
for d = 1.750
x4 will be negative so we stop here
so the distance from speaker here is given below
distance = 2.5 + x
here x = 0.475 , 3.125 and 15.375 so
distance 1 = 2.5 + 0.475 = 2.975 m
distance 2 = 2.5 + 3.125 = 5.625 m
distance 3 = 2.5 + 15.375 = 17.875 m
final distance from speaker is 17.87 m