Answer:
Explanation:
There are a lot of assumptions needed for the calculation:
first is the speaker is a point source
second the speaker is 100% efficient in its output
third the sound output propagates as a sphere
Intensity = Power / Surface Area
= 70 / (4*pi*8.20^2)
= 0.082W/m^2
Converting into dB:
= 10*log ( Intensity / (1*10^-12))
= 10*log(0.0828/ (1*10^-12))
= 109 dB
Answer:
Explanation:
The fact is that there exists no temperature change until a phase change is complete. That is to say, during a phase change, the energy that will be supplied is used only to separate the molecules. There is no part of it is used to increase the kinetic energy of the molecules. So its temperature will not rise, not really, since the kinetic energy of the molecules remains the same. Also, it should be noted that the average kinetic energy of the molecules does not change at the moment that melting occurs, thus the temperature of the molecules does not change.
The answer is 45 degrees.
According to the Kinematics of projectile motion, if the purpose is to maximize range, optimum angle of landing is always 45 degrees.If the purpose is to maximize range & projection height is zero, the optimum angle of projection (and landing) is 45 degrees.
By Newtons Third law this is an action reaction pair of force
So the momentum is the same
30*20=50*x where x is velocity
x= 12m/s
direction is towards left since they act in opposite directions
