Answer:
(a) 1.08 m
(b) 1.06 m
Explanation:
<u>Step 1:</u> calculate the center of gravity from 20kg mass
Let the center of gravity from 20kg mass = X
Applying the principle of moment; clockwise moment = ant-clockwise moment
20*X = 35*(1.7-X)
20X = 59.5 - 35X
55X = 59.5
X = 59.5/55
X = 1.08 m
Ignoring the weight of the bar, the center of gravity is 1.08m from left end of the barbell.
<u>Step 2:</u> calculate the center of gravity from 20kg mass, if the 8.0kg mass of the barbell in considered.
Applying the principle of moment
20X +2.353X = 59.5 -35X + 4 - 2.353X
59.706X = 63.5
X = 63.5/59.706
X = 1.06 m
considering the weight of the bar, the center of gravity is 1.06m from left end of the barbell.
Expand each vector into their component forms:
Similarly,
Then assuming the resultant vector is the sum of these three vectors, we have
and so has magnitude
and direction such that
Answer:
Power = 124.50 W
Explanation:
Given that:
The Sound intensity of a speaker output is 102 dB
and the distance r = 25 m
For the intensity of sound,
where;
the threshold of hearing
I = 0.01585 W/m²
If we recall, we know remember that ;
Power = Intensity × A
rea
Power = 0.01585 W/m² × 4 × 3.142 × (25 m)²
Power = 124.50 W
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