All you would do is for a, 10 times 2 is 20 so it would be 20-dB
For b, 10 times 4 is 40 so it would be 40-dB
For c, 10 times 8 is 80 so it would be 80-dB
<h2>
Angular acceleration is 80 rad/s²
</h2><h2>
Number of revolutions undergone is 1.02</h2>
Explanation:
We have equation of motion v = u + at
Initial angular velocity, u = 0 rad/s
Final angular velocity, v = 32 rad/s
Time, t = 0.40 s
Substituting
v = u + at
32 = 0 + a x 0.40
a = 80 rad/s²
Angular acceleration is 80 rad/s²
We have equation of motion s = ut + 0.5 at²
Initial angular velocity, u = 0 rad/s
Angular acceleration, a = 80 rad/s²
Time, t = 0.4 s
Substituting
s = ut + 0.5 at²
s = 0 x 0.4 + 0.5 x 80 x 0.4²
s = 6.4 rad
Angular displacement = 6.4 rad
![\texttt{Number of revolutions = }\frac{6.4}{2\pi}=1.02](https://tex.z-dn.net/?f=%5Ctexttt%7BNumber%20of%20revolutions%20%3D%20%7D%5Cfrac%7B6.4%7D%7B2%5Cpi%7D%3D1.02)
Number of revolutions undergone is 1.02
Answer
given,
Distance for decibel reading
r₁ = 13 m
r₂ = 24 m
When the engineer is at r₁ reading is β₁ = 101 dB
now, Calculating the Intensity at r₁
Using formula
![\beta = 10 log(\dfrac{I}{I_0})](https://tex.z-dn.net/?f=%5Cbeta%20%3D%2010%20log%28%5Cdfrac%7BI%7D%7BI_0%7D%29)
I₀ = 10⁻¹² W/m²
now inserting the given values
![101= 10 log(\dfrac{I}{10^{-12}})](https://tex.z-dn.net/?f=101%3D%2010%20log%28%5Cdfrac%7BI%7D%7B10%5E%7B-12%7D%7D%29)
![10.1= log(\dfrac{I}{10^{-12}})](https://tex.z-dn.net/?f=10.1%3D%20log%28%5Cdfrac%7BI%7D%7B10%5E%7B-12%7D%7D%29)
![\dfrac{I}{10^{-12}}= 10^{10.1}](https://tex.z-dn.net/?f=%5Cdfrac%7BI%7D%7B10%5E%7B-12%7D%7D%3D%2010%5E%7B10.1%7D)
![I =10^{10.1} \times 10^{-12}](https://tex.z-dn.net/?f=I%20%3D10%5E%7B10.1%7D%20%5Ctimes%2010%5E%7B-12%7D)
I = 0.01258 W/m²
now, calculating power at r₁
P₁ = I₁ A₁
P₁ = 0.01258 x 4 π r²
P₁ = 0.01258 x 4 π x 13²
P₁ = 26.72 W
Answer:
3.75m/s
Explanation:
Velocity of a body is its displacement divided by time taken;
Velocity =
Displacement is the distance from the starting point.
Here:
------------------------------------------- 20m
40m ------------------------------------------------------------------------------
--------------------------------------------------------------------35m
Displacement = 35m - 20m = 15m
Time taken = 4s
Velocity =
= 3.75m/s