Apenny falls from a windowsill which is 25.0 m above the sidewalk. how much time does a passerby on the sidewalk below have to move out of the way before the penny hits the ground?

Ais useful when you need a simple machine to you separate two things. a. lever b. screw c. pulley d. wedge

An important dimensionless parameter concerned with very high-speed flow is the mach number, defined as v/c, where v is the speed of the object such as an airplane or projectile, and c is the speed of sound in the fluid surrounding the object. for a projectile traveling at 1170 mph through air at 50 ˚f and standard atmospheric pressure, what is the value of the mach number?

A14 kg rock starting from rest free falls through a distance of 5.0 m with no air resistance. find the momentum change of the rock caused by its fall and the resulting change in the magnitude of earths velocity. earth mass is 6.0 * 10^24 kg. show your work assuming the rock earth system is closed.