Saturday
April 30, 2016

# Homework Help: physics (please check work)

Posted by Diane on Sunday, December 10, 2006 at 1:32pm.

A uniform rod AB is 1.2 m long and weighs 16N. It is suspended by strings AC and BD. A block P weighing 96N is attached at E, 0.30N from A. The tension force in the string BD has a magnitude.

My work:
Taking torque around AC string
clockwise=counterclockwise
block P + Board force down= BD tension
(0.3m * 96N)+ (.6m * 16N)= BD (1.2m)
38.4= BD(1.2m)
BD= 32N

An 800N man stands halfway up a 5.0m long ladder of negligible weight. The base of the ladder is 3.0m from the wall. Assuming that the wall-ladder contact is frictionless, the wall pushes against the ladder with a force magnitude of:

my work:

cos (theta) = 3m/5m
theta= 53.13 degrees

horizontal components
Ff (friction foce on bottom) - FN (normal force on top) = 0

Ff=FN

vertical components:
Torque taken from top point of ladder
clockwise= counterclockwise
(800N X 2.5X cos(53.1))= FN(5)
FN=240N

Thank you