If the lens in a person's eye is too highly curved, this person is suffering from: nearsightedness.
lens is a piece of transparent material (such as glass) that has two opposite regular surfaces either both curved or one curved and the other plane and that is used either singly or combined in an optical instrument for forming an image by focusing rays of light.
The lens is used to form an image of an object by focusing rays of light from the object.
Various types of lenses are :
- Concave lens.
- Convex lens.
- Plano lens.
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Answer:
66.98 db
Explanation:
We know that

L_T= Total signal level in db
n= number of sources
L_S= signal level from signal source.

= 66.98 db
Answer: 1.289 m
Explanation:
The path the cobra's venom follows since it is spitted until it hits the ground, is described by a parabola. Hence, the equations for parabolic motion (which has two components) can be applied to solve this problem:
<u>x-component:
</u>
(1)
Where:
is the horizontal distance traveled by the venom
is the venom's initial speed
is the angle
is the time since the venom is spitted until it hits the ground
<u>y-component:
</u>
(2)
Where:
is the initial height of the venom
is the final height of the venom (when it finally hits the ground)
is the acceleration due gravity
Let's begin with (2) to find the time it takes the complete path:
(3)
Rewritting (3):
(4)
This is a quadratic equation (also called equation of the second degree) of the form
, which can be solved with the following formula:
(5)
Where:
Substituting the known values:
(6)
Solving (6) we find the positive result is:
(7)
Substituting (7) in (1):
(8)
We finally find the horizontal distance traveled by the venom:
You can't change time to a measurement of distance
Answer:
Power_input = 85.71 [W]
Explanation:
To be able to solve this problem we must first find the work done. Work is defined as the product of force by distance.

where:
W = work [J] (units of Joules)
F = force [N] (units of Newton)
d = distance [m]
We need to bear in mind that the force can be calculated by multiplying the mass by the gravity acceleration.
Now replacing:
![W = (80*10)*3\\W = 2400 [J]](https://tex.z-dn.net/?f=W%20%3D%20%2880%2A10%29%2A3%5C%5CW%20%3D%202400%20%5BJ%5D)
Power is defined as the work done over a certain time. In this way by means of the following formula, we can calculate the required power.

where:
P = power [W] (units of watts)
W = work [J]
t = time = 40 [s]
![P = 2400/40\\P = 60 [W]](https://tex.z-dn.net/?f=P%20%3D%202400%2F40%5C%5CP%20%3D%2060%20%5BW%5D)
The calculated power is the required power. Now as we have the efficiency of the machine, we can calculate the power that is introduced, to be able to do that work.
![Effic=0.7\\Effic=P_{required}/P_{introduced}\\P_{introduced}=60/0.7\\P_{introduced}=85.71[W]](https://tex.z-dn.net/?f=Effic%3D0.7%5C%5CEffic%3DP_%7Brequired%7D%2FP_%7Bintroduced%7D%5C%5CP_%7Bintroduced%7D%3D60%2F0.7%5C%5CP_%7Bintroduced%7D%3D85.71%5BW%5D)