A 14.0-m uniform ladder weighing 510 N rests against a frictionless wall. The la
ID: 1551706 • Letter: A
Question
A 14.0-m uniform ladder weighing 510 N rests against a frictionless wall. The ladder makes a 57.0° angle with the horizontal.
(a) Find the horizontal and vertical forces the ground exerts on the base of the ladder when an 820-N firefighter has climbed 4.10 m along the ladder from the bottom.
Horizontal Force
Vertical Force
(b) If the ladder is just on the verge of slipping when the firefighter is 8.90 m from the bottom, what is the coefficient of static friction between ladder and ground?
Explanation / Answer
a)
here
Ng = 820 + 510 = 1330 N up the wall
then
torque(wall) = torque(firefighter) + torque(ladder)
Nw * cos28.5 * 14 = 820 * 4.1 * sin28.5 + 510 * 7 * sin28.5
Nw = 268.85 N to the left
Ff = 268.85 N to the right
b)
cos28.5 * Nw * 14 = 820 * 8.9 * sin28.5 + 510 * 7 * sin28.5
Nw = 421.5 N
then
Nw = u * Ng
1330 * u= 421.5
u = 0.316
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.