Physics 101 Lecture Notes - Lecture 25: Parachuting

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carmineeel944

26 Nov 2018

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Document Summary

Drag always opposes the motion; it is a resistive force. The faster an object, the more drag it experiences. A = cross section area p = the density of air = 1. 2 (kg/m 3 ) Cross section area varies depending on the shape of the object. When f net = 0, the speed is constant. A skydiver in a freefall attains a terminal speed of v term . If the cross sectional are is a , the density of the are is 1. 20(kg/m 3 ), and the drag coefficient is c , calculate the skydiver"s mass. F g = d mg = ( )cpav 2 m = (cpav 2 )/(2g) The skydiver from problem i wants to decrease his terminal speed to. A = (2mg)/(cpv 2 ) (pi)r 2 = (2mg)/(cpv 2 ) r = {[(2mg)/(cpv 2 )]/(pi)} d = 2r.

Related Questions

The force, $F$ of the wind blowing against a building is given
by F=C_D ρ V² A/2 where V is the wind speed, $\rho$ the density of
the air, A the cross-sectional area cf the building, and _D is a constant termed the drag coefficient. Determine the dimensions of the
drag coefficient.

amberhound675

The dominant form of drag experienced by vehicles (bikes, cars, planes, etc.) at operating speeds is called form drag. It increases quadratically with velocity (essentially because the amount of air you run into increases with v and so does the amount of force you must exert on each small volume of air). Thus ,where A is the cross-sectional area of the vehicle and Cd is called the coefficient of drag.

Consider a vehicle moving with constant velocity
a)Find the power dissipated by form drag.

b) A certain car has an engine that provides a maximum power P₀. Suppose that the maximum speed of the car, v₀, is limited by a drag force proportional to the square of the speed (as in the previous part). The car engine is now modified, so that the new power P₁ is 10 percent greater than the original power (P₁=110%P₀).

Assume the following:

The top speed is limited by air drag.
The magnitude of the force of air drag at these speeds is proportional to the square of the speed.

By what percentage, (v₁−v₀)/v₀, is the top speed of the car increased?