2. what are some of the ways that scientists classify the objects that they see in the hubble deep field images? what are some of the challenges scientists face when doing this? 3. when measuring distances, astronomers sometimes find that a small object in the sky is closer to earth than a larger object. how can this be?

When the force acting on an object points at least partially in the direction of the motion the work done is considered to be negative

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.

Which subatomic particle has a negative charge