a light bulb is 4.1 m from a surface. how much luminous flux must the bulb produce if the illuminance required is 22 lx?
1 answer:
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Answer:
v = 54.2 m / s
Explanation:
Let's use energy conservation for this problem.
Starting point Higher
Em₀ = U = m g h
Final point. Lower
= K = ½ m v²
Em₀ = Em_{f}
m g h = ½ m v²
v² = 2gh
v = √ 2gh
Let's calculate
v = √ (2 9.8 150)
v = 54.2 m / s
The Young modulus is given by:
where
F is the force applied
is the initial length of the wire
is the cross-sectional area of the wire
is the stretch of the wire
The wire in the problem stretches by
of its length, this means
We can also calculate the area of the wire; its radius is in fact half the diameter:
and so the area is
We know the force applied to the wire, F=20 N, so now we have everything to calculate the Young modulus:
where
F is the force applied
The wire in the problem stretches by
We can also calculate the area of the wire; its radius is in fact half the diameter:
and so the area is
We know the force applied to the wire, F=20 N, so now we have everything to calculate the Young modulus:
Answer:
Explanation:
Let T be the tension in the swing
At top point
where v=velocity needed to complete circular path
r=distance between point of rotation to the ball center=L+\frac{d}{2} (d=diameter of ball)
Th-resold velocity is given by
To get the velocity at bottom conserve energy at Top and bottom
At top
Energy at Bottom
Comparing two as energy is conserved