A cart is moving along and very close to a level air track at a speed of 0.36 m/s. The surface area of the cart’s underside is 2.7 × 10–2 m2 and the thickness of the air layer between the cart and the track is 5.2 × 10–5 m. The air temperature is 20°C. a) Find the magnitude of the retarding force, in newtons, acting on the cart due to the viscosity of the air layer between the cart and the air track. Take the viscosity of air at the given temperature to be 1.81 × 10–5 Pa⋅s. b) What is the ratio of this force to the weight of the 0.325 kg cart?
Viscosity
The measure of the resistance of a fluid to flow is known as viscosity. Most fluids have some resistance to motion, the resistance provided by the fluid is called viscosity. This resistance is created by the force of attraction between the fluid molecules. If you pour water through a funnel, it flows easily and quickly, because it has very little resistance. But if you pour honey through a funnel, it may take a little time longer, as the density of honey is high.
Poiseuille's Law
The law of Poiseuille or Poiseuille's equation states that the pressure drop of an incompressible fluid especially a liquid in a laminar flow that passes through a cylindrical tube of length L, radius r, pressure gradient ΔP, and mainly depends on the viscosity of the fluid is nothing but the pressure difference of the layers of fluids. ΔP=P1-P2
Drag Forces
Forces that occur due to the movement of fluid are known as fluid mechanics. Following are the fluids present:
A cart is moving along and very close to a level air track at a speed of 0.36 m/s. The surface area of the cart’s underside is 2.7 × 10–2 m2 and the thickness of the air layer between the cart and the track is 5.2 × 10–5 m. The air temperature is 20°C.
a) Find the magnitude of the retarding force, in newtons, acting on the cart due to the viscosity of the air layer between the cart and the air track. Take the viscosity of air at the given temperature to be 1.81 × 10–5 Pa⋅s.
b) What is the ratio of this force to the weight of the 0.325 kg cart?
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