To transport a series of bundles of shingles A to a roof, a
contractor uses a motor-driven lift consisting of a horizontal
platform BC which rides on rails attached to the sides of a
ladder. The lift starts from rest and initially moves with a
constant acceleration a₁ as shown. The lift then decelerates
at a constant rate a2 and comes to rest at D, near the top of
the ladder. Knowing that the coefficient of static friction
between a bundle of shingles and the horizontal platform is
0.30, determine the largest allowable acceleration a₁ and the
largest allowable deceleration as if the bundle is not to slide
on the platform.
0.8 m
B
65°
Fig: 1