Answer:
harmful effects
1. that will cause air pollution
2. that will destroy our earth
Image from a far away object formed by a concave mirror
I have no idea but this is my best guess as a sophomore in college
Answer:

Explanation:
For the simple pendulum problem we need to remember that:
,
where
is the angular position, t is time, g is the gravity, and L is the length of the pendulum. We also need to remember that there is a relationship between the angular frequency and the length of the pendulum:
,
where
is the angular frequency.
There is also an equation that relates the oscillation period and the angular frequeny:
,
where T is the oscillation period. Now, we can easily solve for L:

Answer:
Time take to fill the standing wave to the entire length of the string is 1.3 sec.
Explanation:
Given :
The length of the one end
, frequency of the wave
= 2.3 Hz, wavelength of the wave λ = 1 m.
Standing wave is the example of the transverse wave, standing wave doesn't transfer energy in a medium.
We know,
∴
λ
Where
speed of the standing wave.
also, ∴ 
where
time take to fill entire length of the string.
Compare above both equation,
⇒
sec

Therefore, the time taken to fill entire length 0f the string is 1.3 sec.