Adrag racing car with a weight of 1600 lbf attains a speed of 270 mph in a quarter-mile race. immediately after passing the timing lights, the driver opens a drag chute. at this point, the air and rolling resistance of the car are negligible compared to the drag of the chute. what chute diameter (in feet) is required to make sure that the car decelerates to 60 mph within 7 seconds?

15.065ft

Explanation:

To solve this problem it is necessary to consider the aerodynamic concepts related to the Drag Force.

By definition the drag force is expressed as:

Where

is the density of the flow

V = Velocity

= Drag coefficient

A = Area

For a Car is defined the drag coefficient as 0.3, while the density of air in normal conditions is 1.21kg/m^3

For second Newton's Law the Force is also defined as,

Equating both equations we have:

Integrating

Here,

Replacing:

if the thermos has a vacuum innner, then heat through conv currents and conduction are reduced = vacuum flask

more than, less

less than, more