Answer:
The weight of the girl = 1045.86 kg/m³
Explanation:
Density: This can be defined as the ratio of the mass of a body to the volume of that body. The S.I unit of density is kg/m³.
From Archimedes principle,
R.d = Density of the person/Density of water = Weight of the person in air/Upthrust.
⇒ D₁/D₂ = W/U............................... Equation 1.
Where D₁ = Density of the person, D₂ = Density of water, W = Weight of the person in air, U = Upthrust in water.
Making D₁ the subject of the equation,
D₁ = D₂(W/U)................................... Equation 2
<em>Given: D₂ = 1000 kg/m³ , W = 509.45 N, U = lost in weight = weight in air - weight in water = 509.45 - 22.34 = 487.11 N</em>
<em>Substituting these values into equation 2</em>
D₁ = 1000(509.45/487.11)
D₁ = 1045.86 kg/m³
Thus the weight of the girl = 1045.86 kg/m³
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Answer:
576 joules
Explanation:
From the question we are given the following:
weight = 810 N
radius (r) = 1.6 m
horizontal force (F) = 55 N
time (t) = 4 s
acceleration due to gravity (g) = 9.8 m/s^{2}
K.E = 0.5 x MI x ω^{2}
where MI is the moment of inertia and ω is the angular velocity
MI = 0.5 x m x r^2
mass = weight ÷ g = 810 ÷ 9.8 = 82.65 kg
MI = 0.5 x 82.65 x 1.6^{2}
MI = 105.8 kg.m^{2}
angular velocity (ω) = a x t
angular acceleration (a) = torque ÷ MI
where torque = F x r = 55 x 1.6 = 88 N.m
a= 88 ÷ 105.8 = 0.83 rad /s^{2}
therefore
angular velocity (ω) = a x t = 0.83 x 4 = 3.33 rad/s
K.E = 0.5 x MI x ω^{2}
K.E = 0.5 x 105.8 x 3.33^{2} = 576 joules
As we know the formula of kinetic energy is
here given that
KE = 150,000 J
mass = 120 kg
we can use this to find speed
So speed of above object is 50 m/s
Uhhhh...you should have paid attention in class, just saying...
