16 wooden hangers were built for US navy airships. The hangers were 300 m long and had a max height of 52 m. imagine a 40 kg block being lifted by a winch fromt he ground to the top of the hangers ceiling. if the winch does 20800 J of work in lifting the block, what force is exerted in them?
2006-12-11 15:42:53 · 1 answers · asked by maggie 1 in Science & Mathematics ➔ Physics
The work done is the change in potential energy of the block. W=m*g*h. This does not depend on the force. If more energy than that is used, then the remainder must represent frictional loss. The energy lost to friction is Fr * h, where Fr is the frictional force. Therefore
Fr * h = E - m*g*h, or Fr = E/h - m*g
The total force then is the force to overcome gravity = m*g plus Fr
Ft = m*g + E/h - m*g = E/h For E = 20800J and h=53m, this comes out 400N.
2006-12-11 16:01:14 · answer #1 · answered by gp4rts 7 · 0⤊ 0⤋