A painter foolishly leans his ladder against a frictionless window. The ladder i

Question

A painter foolishly leans his ladder against a frictionless window. The ladder is 8m long and has a mass of 30kg. He has leaned the ladder at an angle of 70 degrees to the horizontal, the coefficient of the static friction between the ladder and the ground is 0.4, and the mass of the painter is 80kg. The painter climbs up the ladder 5m.

a) What is the normal force on the ladder from the ground (use Fy=may)?

b) What is the normal force on the ladder from the window (use torque=Ia)?

c) The window will break if the normal force is greater than 300N. As the painter climbs up the ladder, which will happen first, the window breaking or the ladder slipping (use Fx=max)?

d) How far along the ladder can the painter climb before the window breaks or the ladder slips?

Explanation / Answer

a) normal force on the ladder from the ground = (m_painter *g *sin70) + (m_ladder *g *sin70) =1012.99 N

b) What is the normal force on the ladder from the window = frictional force on ladder = 0.4 * 1012.99 = 405.19 N

c) ladder slipping

d) 6.5 m

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