An 80-kilogram skier slides on waxed skis along a horizontal surface of snow at constant velocity while pushing with his poles.
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Answer:
a) W = 46.8 J and b) v = 3.84 m/s
Explanation:
The energy work theorem states that the work done on the system is equal to the variation of the kinetic energy
W = ΔK = -K₀
a) work is the scalar product of force by distance
W = F . d
Bold indicates vectors. In this case the dog applies a force in the direction of the displacement, so the angle between the force and the displacement is zero, therefore, the scalar product is reduced to the ordinary product.
W = F d cos θ
W = 39.0 1.20 cos 0
W = 46.8 J
b) zero initial kinetic language because the package is stopped
W - =
-K₀
W - fr d= ½ m v² - 0
W - μ N d = ½ m v
on the horizontal surface using Newton's second law
N-W = 0
N = W = mg
W - μ mg d = ½ m v
v² = (W -μ mg d) 2/m
v = √(W -μ mg d) 2/m
v = √[(46.8 - 0.30 4.30 9.8 1.20) 2/4.3 ]
v = √(31.63 2/4.3)
v = 3.84 m/s
The inlet velocity is 1.4 m/s and inlet volume is 0.019 m³/s.
Explanation:
When water entering the tube of constant diameter flows through the tube, it exhibits continuity of mass in the hydrostatics. So the mass of water moving from the inlet to the outlet tend to be same, but the velocity may differ.
As per mass flow equality which states that the rate of flow of mass in the inlet is equal to the product of area of the tube with the velocity of the water and the density of the tube.
Since, the inlet volume flow is measured as the product of velocity with the area.
Inlet volume flow=Inlet velocity*Area*time
And the mass flow rate is
Mass flow rate in the inlet=density*area*inlet velocity*time
Mass flow rate in the outlet=density*area*outlet velocity*time
Since, the time and area is constant, the inlet and outlet will be same as
(Mass inlet)/(density*inlet velocity)=Area*Time
(Mass outlet)/(density*outlet velocity)=Area*Time
As the ratio of mass to density is termed as specific volume, then
(Specific volume inlet)/(Inlet velocity)=(Specific volume outlet)/(Outlet velocity)
Inlet velocity= (Specific volume inlet)/(Specific volume outlet)*Outlet velocity
As, the specific volume of water at inlet is 0.001017 m³/kg and at outlet is 0.05217 m³/kg and the outlet velocity is given as 72 m/s, the inlet velocity
is
So, the inlet velocity is 1.4035 m/s.
Then the inlet volume will be
As the diameter of tube is 130 mm, then the radius is 65 mm and inlet velocity is 1.4 m/s
So, the inlet volume is 0.019 m³/s.
Thus, the inlet velocity is 1.4 m/s and inlet volume is 0.019 m³/s.