Physics please help????? plank problem?
A plank 4.6 m long and weighing 123 N has its left end resting on a block and the other end supported by a rope. The plank is in the horizontal position. If the greatest tension the rope can withstand is 422 N, how far from the block can a 63.4 kg girl walk out on the plank before the rope breaks?
Comments
let d be distance from the block
taking moment about point of contact at the block
422 * 4.6 = 123 * 2.3 + 63.4 * 9.81 * d
anti clockwise moment = clockwise moment
d= 2.666 m ---answer