We are given that the system “releases” heat of 2,500 J,
and that it “does work on the surroundings” by 7,655 J.
The highlighted words releases and does work on the surroundings
all refers to that it is the system itself which expends energy to do those
things. Therefore the action of releasing heat and doing work has both magnitudes
of negative value. Therefore:
heat released = - 2, 500 J
work done = - 7, 655 J
Which means that the total internal energy change of the
system is:
change in internal energy = heat released + work
<span>change in internal energy = - 2, 500 J + - 7, 655 J</span>
<span>change in internal energy = -10,155 J</span>
Answer:
Explanation:
<u>Accelerated Motion</u>
It occurs when an object changes its speed over time. If the changes in speed are uniform, then the acceleration is constant, positive if the speed increases, negative if the speed decreases.
The acceleration is calculated as follows:
The aeroplane starts with a speed of vo=62 m/s and reaches a speed of vf=6 m/s in t=35 s.
The acceleration is:
Answer:
the photons (quanta of light) collide with the electrons, these electrons have to overcome the threshold energy that is the energy of union with the metal, and the energy that remains is converted to kinetic energy.
K = E - Ф
Explanation:
The photoelectric effect is the emission of electrons from the surface of a metal.
This was correctly explained by Einstein, in his explanation the energy of the photons (quanta of light) collide with the electrons, these electrons have to overcome the threshold energy that is the energy of union with the metal, and the energy that remains is converted to kinetic energy.
E = hf
E = K + Ф
K = E - Ф
The energy of the photons is given by the Planck relation E = hf and according to Einstein the number of joints must be added
E = n hf
Therefore, depending on the value of this energy, the emitted electrons can have energy from zero onwards.
Answer:
20.2 seconds
Explanation:
The airplane (and therefore the crate) initially has no vertical velocity, so v₀ = 0 m/s.
The crate is in free fall, so a = -9.8 m/s².
The crate falls downward, so Δx = -2000 m.
Find: t, the time it takes for the crate to land.
Δx = v₀ t + ½ at²
-2000 m = (0 m/s) t + ½ (-9.8 m/s²) t²
t = 20.2 s
It takes 20.2 seconds for the crate to land.
Answer:
Explanation:
We shall represent all the forces in vector form .
Force of 95 pounds
F₁ = 95cos100 i + 95sin100j
= -16.5 i +93.55 j
force of 75 pounds
F₂ = 75cos200 + 75sin200j
= -70.47 i - 25.65 j
force of 146 pounds
F₃ = 146cos300 i + 146sin300j
= 73i -126.44 j
Resultant force
R = F₁+ F₂ + F₃
= -16.5 i +93.55 j -70.47 i - 25.65 j +73i -126.44 j
= -13.97 i - 58.54 j
Magnitude of R = √ ( 13.97² + 58.54² )
= 60.18
If Ф be angle of resultant with axis
tanФ = - 58.54 / -13.97
Ф = 76.57 + 180 = 256.57 , because both x and y components are negative. So the resultant will be in third quadrant.
