A skateboarder rolls horizontally off the top of a staircase and lands at the bottom. The staircase has a horizontal length of 12.0 m with a vertical drop of 2.00 m. We can ignore air resistance. What is the skater's initial horizontal velocity?

The percent efficiency of a machine can never be 100% (or greater), because in the real world some energy is always converted into a. heat b. work c. input force d. output force

Explain the consequences of this addiction to the brain tissue

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.