The speedof a boat in still water is v. the boat is to make a round-trip ina river whose current travels at speed u. derive a formula for thetime needed to make a round trip of total distance d if the boatmakes the round trip by moving (a) upstream and back downstream,(b) directly across the river and back. we must assume u < v; why?

The of a machine determines its "usefulness." a. input force b. output force c. mechanical advantage

Aprojectile is launched from ground level with an initial velocity of v 0 feet per second. neglecting air resistance, its height in feet t seconds after launch is given by s equals negative 16 t squared plus v 0 t. find the time(s) that the projectile will (a) reach a height of 192 ft and (b) return to the ground when v 0equals112 feet per second. (a) find the time(s) that the projectile will reach a height of 192 ft when v 0equals112 feet per second. select the correct choice below and, if necessary, fill in the answer box to complete your choice.

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.