Its B: reduce the amount of energy needed to do the work by putting the work onto something else
Angry sound level = 70 db
Soothing sound level = 50 db
Frequency, f = 500 Hz
Assuming speed of sound = 345 m/s
Density (assumed) = 1.21 kg/m^3
Reference sound intensity, Io = 1*10^-12 w/m^2
Part (a): Initial sound intensity (angry sound)
10log (I/Io) = Sound level
Therefore,
For Ia = 70 db
Ia/(1*10^-12) = 10^(70/10)
Ia = 10^(70/10)*10^-12 = 1*10^-5 W/m^2
Part (b): Final sound intensity (soothing sound)
Is = 50 db
Therefore,
Is = 10^(50/10)*10^-12 = 18*10^-7 W/m^2
Part (c): Initial sound wave amplitude
Now,
I (W/m^2) = 0.5*A^2*density*velocity*4*π^2*frequency^2
Making A the subject;
A = Sqrt [I/(0.5*density*velocity*4π^2*frequency^2)]
Substituting;
A_initial = Sqrt [(1*10^-5)/(0.5*1.21*345*4π^2*500^2)] = 6.97*10^-8 m = 69.7 nm
Part (d): Final sound wave amplitude
A_final = Sqrt [(1*10^-7)/(0.5*1.21*345*4π^2*500^2)] = 6.97*10^-9 m = 6.97 nm
Answer:
10.21 N
Explanation:
As the force is a vector, it can be decomposed in two components perpendicular each other, so there is no projection of one component in the direction of the other.
When divided in this way, the magnitude of the resultant vector can be found simply applying trigonometry, as follows:
F² = Fx² + Fy² ⇒ F = √(Fx)²+(Fy)²
Replacing by Fx= 5.17 N and Fy = 8.8 N, we get:
F = √(5.17)²+(8.8)² =10.21 N
Answer:
1945.6 W
Explanation:
We are given that
Height,h=1100 m
Time,t=37.5 min=
1 min=60 s
Mass,m=65 kg
Power,P=700 W
We have to find the his total metabolic power.
Power,=
Where 
Efficiency =25%
Therefore,Power,P'=
Total metabolic power=P+P'=700+1245.6=1945.6 W
1# The ball flying through the air has two types of energy, kinetic from its velocity and potential from its height off the ground.
