It is given that for the convex lens,
Case 1.
u=−40cm
f=+15cm
Using lens formula
v
1
−
u
1
=
f
1
v
1
−
40
1
=
15
1
v
1
=
15
1
−
40
1
v=+24.3cm
The image in formed in this case at a distance of 24.3cm in left of lens.
Case 2.
A point source is placed in between the lens and the mirror at a distance of 40 cm from the lens i.e. the source is placed at the focus of mirror, then the rays after reflection becomes parallel for the lens such that
u=∞
f=15cm
Now, using mirror’s formula
v
1
+
u
1
=
f
1
v
1
+
∞
1
=
15
1
v=+15cm
The image is formed at a distance of 15cm in left of mirror
The level of greenhouse gases in our atmosphere would decrease, due to less automobiles.
Time = (distance) / (speed)
Time = (4.12x10^16 m) / (3 x10^8 m/s)
Time = 1.37 x 10^8 seconds
Divide the seconds by 86,400 to get days. Then divide the days by 365 to get years.
Time = about 4.35 years
Answer:
-5.8868501529 m/s² or -5.8868501529g
0.118909090909 s
Explanation:
t = Time taken
u = Initial velocity
v = Final velocity
s = Displacement
a = Acceleration
g = Acceleration due to gravity = 9.81 m/s²

Dividing by g

The acceleration is -5.8868501529 m/s² or -5.8868501529g

The time taken is 0.118909090909 s
To develop this problem it is necessary to apply the concepts related to Sound Intensity.
By definition the intensity is given by the equation

Where,
I = Intensity of Sound
= Intensity of Reference
At this case we have that 15 engines produces 15 times the reference intensity, that is

And the total mutual intensity is 100 dB, so we should




Therefore each one of these engines produce D. 88dB.