A train moves at a constant velocity of 50 km/h. How far will it move in 0.5 hour?

Which of the following represents a virtual image?

The speed of light in a material is 0.50 c. what is the critical angle of a light ray at the interface between the material and a vacuum?

The ratio of lift to drag l/d for a wing or airfoil is an important aerodynamic parameter, indeed, it is a direct measure of the aerodynamic efficiency of the wing. if a wing is pitched through a range of angle of attack, l/d first increases, then goes through a maximum, and then decreases. consider an infinite wing with an naca 2412 airfoil. estimate the maximum value of l/d. assume that the reynolds number is 9x10^6.