Where will water evaporate from?
1 answer:
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Answer:
4.15 m/s
Explanation:
As the total energy must be conserved (neglecting air resistance) the change in gravitational potential energy, must be equal to the change in kinetic energy:
ΔE = ΔK + ΔU =0
If we take as a zero reference level for the gravitational potential energy, the height of the swing seat above the ground, (which is equal to 0.21 m), we can find the initial gravitational energy, considering the height of the point where the seat is released, regarding this point:
h₀ = 1.09 m -0.21 m = 0.88 m
⇒ U₀ = m*g*h₀ = 400 N*0.88 m = 352 J
As Uf = 0, ΔU = Uf -U₀ = -352 J
As the swing starts from rest, K₀=0, so we can say:
ΔK = Kf = (1)
As ΔK = -ΔU ⇒ ΔK = 352 J (2)
From (1) and (2) we can solve for vf, as follows:
So, when the swing passes through its lowest position, Betty moves at 4.15 m/s.
1. 0.2 g/mL
The relationship between mass, density and volume of an object is
where
d is the density
m is the mass
V is the volume
For the object in this problem, we have
m = 10 g
V = 50 mL
Substituting into the equation,
2. 10 mL
In this exercise we know:
- The density of the object: d = 2 g/mL
- The mass of the object: m = 20 g
Therefore, we can re-arrange the previous equation to find the volume:
And substituting values into the equation, we find