Question

When a pilot increases the angle of attack on a symmetrical airfoil, the center of pressure will:

A. move forward.
B. Move aft.
C. Be unchanged.

Answer 1

The center of pressure on a symmetrical airfoil moves forward when the angle of attack increases. Kinetic energy decreases with a rearward drag force. The pitch of a sound increases as the source moves toward you due to the Doppler effect.

Step-by-step explanation:

Regarding the initial question about the effect of increasing the angle of attack on a symmetrical airfoil, we need to consider the aerodynamics involved. As the angle of attack increases, the distribution of pressures around the airfoil changes. However, for a symmetrical airfoil, the center of pressure generally moves forward as the angle of attack increases, up to the point of stall. This is because the increased angle of attack causes an asymmetrical flow of air, increasing pressure on the leading half of the airfoil.

Looking at the provided reference information, we can analyze a few of the points:

• Regarding the kinetic energy question, the airplane experiences a net force due to drag, which acts rearward and thus would cause the kinetic energy to decrease. So, if we ignore any lifting force and only consider drag, the correct answer would be 'b. decrease, 40 kN', as the 40 kN drag force is working against the plane's motion.
• When considering the motion of helicopters and yoyos, the upward and downward forces acting on them are external because they come from interactions with the air, and the direction of the yoyo after being released depends on the force applied to it.
• When the source of a sound is moving toward you, the pitch of the sound you hear will increase if the speed of the source increases due to the Doppler effect, making 'a. The sound will become more high-pitched.' the correct answer.

Finally, discussing physics principles related to motion, what individuals feel when an airplane takes off or a car turns sharply is different from what is actually happening according to Newton's first law of motion. The feeling of being pushed back or to the side is due to inertia, the tendency of an object to maintain its state of motion unless acted upon by a force.