Which of the following is an example of how a scientist might use a model
a- a stopwatch is used to time the rate of a chemical reaction
b- a microscope is used to magnify a group of cells
c- a wrench is used to tighten a nut onto a piece of wood
d- the end of a slinky is moved vertically up and down to stimulate a wave

A200-n force is applied to the foot-operated air pump. the return spring s exerts a 2.6-n·m moment on member oba for this position. determine the corresponding compression force c in the cylinder bd. if the diameter of the piston in the cylinder is 40 mm, estimate the air pressure generated for these conditions. state any assumptions. enter a positive number for the compression force c.