Which action is not an example of work? picking up a box off the floor

pushing a box across the floor

holding a tray in the cafeteria line

raising a barbell over your head

Aman does 500 j of work pushing a car a distance of 2 m. how much force does he apply? assume there is no friction. a. 250 n b. 1000 n c. 125 n d. 500 n

The rigid beam is supported by the three suspender bars. bars ab and ef are made of aluminum and bar cd is made of steel. if each bar has a cross-sectional area of 450 mm2, determine the maximum value of p if the allowable stress is (σallow)st = 200 mpa for the steel and ( σallow)al = 150 mpa for the aluminum. est = 200 gpa and eal = 70 gpa.

"an open tank has the shape of a right circular cone. the tank is 6 feet across the top and 5 feet high. how much work is done in emptying the tank by pumping the water over the top edge? note: the density of water is 62.4 lbs per cubic foot."