Question

Two fixed frictionless inclined planes, making angles 30° and 60° with the vertical, are shown in the figure. Two blocks A and B are placed on these planes. The relative vertical acceleration of A with respect to B is

(1) 9.8 ms^-2

(2) 4.9 ms^-2

(3) 2.45 ms^-2

(4) zero

Answer 1

(2) 4.9 ms^-2

Acceleration of A down the plane is g sin 60 = g cos 30° as shown in Fig. Resolve acceleration into horizontal and vertical components as shown in Fig. Obvisouly

The vertical acceleration of A

Similarly the vertical acceleration of B

∴ Relative vertical acceleration of A with respect to B