Answer:
Resonance depends on objects, this may happen for example when you play guitar in a given room, you may find that for some notes the walls or some object vibrate more than for others. This is because those notes are near the frequency of resonance of the walls.
So waves involved are waves that can move or affect objects (in this case the pressure waves of the sound, and the waves that are moving the wall).
this means that the waves are mechanic waves.
Now, in electromagnetics, you also can find resonance frequencies for electromagnetic waves trapped in things called cavities, but this is a different topic.
Density offers a convenient means of obtaining the mass of a body from its volume or vice versa; the mass is equal to the volume multiplied by the density (M = Vd), while the volume is equal to the mass divided by the density (V = M/d).
M = V d
M = 1.4 * 2 = 2.8 kg
Answer: You do not specify what is being asked for. ∆E? ∆H?
∆E = (430 - 238) J = 192 J
∆H = 430 J
Explanation:
If asked for the value of ∆H the answer is simply the change in heat, and in the question, it states introduction of 430 J of heat is causing the system to expand.
Therefore ∆H = 430 J
If asked for ∆E, we know that ∆E = ±q (heat) + work (-P∆V) = ±q + w
The question states that 238 J of work are done AND the system expanded
(work is negative because expansion means work is done BY the system, releasing energy/heat... Conversely, if the system were compressed, work is done ON the system, absorbing heat/energy)
Therefore, ∆E = (430 - 238) J = 192 J
