The correct answer is:
<span>C) The actual frequency of the siren does not change despite appearances.
In fact, Bob will observe an increase in the apparent frequency as the emergency vehicle approaches him, while Jill will observe a decrease in the apparent frequency as the emergency vehicle moves away from him, because of the Doppler effect (the relative velocity between the observer and the source of the sound is changing), but this effect involves the apparent frequency, while the real frequency of the siren will remain the same.</span>
Answer:
The magnitude of applied force,parallel to the incline is 575.38 N and parallel to the floor is 605 N.
Explanation:
Given:
Mass of the piano
= 190 kg
Inclined angle
= 18 degree
Considering gravity,
= 9.8
And
Using,
and 
<em>FBD diagram is attached with all the force acting on the floor and and the inclined. </em>
We have to find the magnitude of forces,when the man pushes it parallel to the incline and to the floor.
a.
When the man pushes it parallel to the incline.
Balancing the forces as
.
⇒ 
⇒ 
⇒ Here it is negative as the force is acting downward.
⇒ Plugging the values of mass
and angle
.
⇒ 
⇒
N
b.
When the force is parallel to the floor.
⇒ 
⇒ 
⇒ Plugging the values.
⇒ 
⇒
N
So,
The magnitude of applied force in inclined direction is 575.38 Newton and parallel to the floor is 605 N.
Answer:
2.80321285141
Explanation:
= Thickness of glass = 4.5 mm
= Thermal conductivity of glass = 0.8 W/mK
= Combined thermal resistance = 
= Thickness of air = 6.6 mm
= Thermal conductivity of air = 0.024 W/mK
The required ratio is the inverse of total thermal resistance

The ratio is 2.80321285141
Answer:
8.4 kW
Explanation:
Using the Stefan-Boltzmann law,
P = εAσT4
Where:
P: Radiation Energy
ε: Emissivity of the Surface. Check emissivity table below of common materials.
A: Surface Area, in m^2.
σ: Stefan-Boltzmann Constant, σ=5.67 × 10-8 W/m2•K4
T: Temperature
Plugging in values,
P = 0.85 x 3.328 x 5.67 x 10^(-8) x 205
P = 8383 W or 8.4 kW