-- There is no need to develop the pictures. They are available immediately in a digital camera.
-- There is no change in the teacher from one picture to the next.
-- The distance the watermelon falls from the teacher in each new picture is more in each picture than in the picture before it. (C)
Cell phones use RF waves from nearby cell towers. RF waves fall in between FM radio waves and microwaves
Answer:
The change in entropy ΔS = 0.0011 kJ/(kg·K)
Explanation:
The given information are;
The mass of water at 20.0°C = 1.0 kg
The mass of water at 80.0°C = 2.0 kg
The heat content per kg of each of the mass of water is given as follows;
The heat content of the mass of water at 20.0°C = h₁ = 83.92 KJ/kg
The heat content of the mass of water at 80.0°C = h₂ = 334.949 KJ/kg
Therefore, the total heat of the the two bodies = 83.92 + 2*334.949 = 753.818 kJ/kg
The heat energy of the mixture =
1 × 4200 × (T - 20) = 2 × 4200 × (80 - T)
∴ T = 60°C
The heat content, of the water at 60° = 251.154 kJ/kg
Therefore, the heat content of water in the 3 kg of the mixture = 3 × 251.154 = 753.462
The change in entropy ΔS = ΔH/T = (753.818 - 753.462)/(60 + 273.15) = 0.0011 kJ/(kg·K).
The answer is A.
Explanation:
We know that the average acceleration a for an interval of time Δt is expressed as:
a = Δv
Δt
where Δv is the change in velocity that occurs during Δt.
e formula for the instantaneous acceleration a is almost the same, except that we need to indicate that we're interested in knowing what the ratio of Δv to Δt approaches as Δt approaches zero.
We can indicate that by using the limit notation.
So, the formula for the instantaneous acceleration is:
a = lim Δv
Δt→0 Δt
Answer:
D) No, because of the way work is defined
Explanation:
The work done on an object is given by:
where
F is the force applied on the object
d is the displacement of the object
is the angle between the direction of the force and the displacement
From the formula, we observe that if there is no motion involved, then the displacement of the object is zero:
d = 0
As a result, the product in the formula is also zero, therefore the work done will be zero as well.
