A constant horizontal force of 30.0 N is exerted by a string attached to a 5.0 kg block being pulled across a tabletop. The block also experiences a frictional force of 5.0 N due to contact with the table. What is the horizontal acceleration of the block?

Does work output exceed work input when a machine is used? a) yes, it does, as machines create energy. b) it depends on the type of machine used. c) no, it doesn’t, as machines are inefficient. d) no, it doesn’t, as machines cannot create energy.

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 branches of natural science include the study of an organism that lived 10 million years ago