Question

The diagram below shows an arrangement of three pulleys A, B, and C. The load is marked as L and the effort as E.

1. Name the Pulleys A, B, and C.
2. Mark in the diagram the directions of load (L), effort (E) and tension T₁ and T₂ in the two strings.
3. How are the magnitudes of L and E related to the tension T₁?
4. Calculate the mechanical advantage and velocity ratio of the arrangement.
5. What assumptions have you made in parts (c) and (d)?

Answer 1

(a) Pulleys A and B are movable pulleys. Pulley C is a fixed pulley.

(b)

(c) L = 4T_1; E = T₁

(d) M.A. = `L/E`

M.A. = `(4T_1)/T_1`

M.A. = 4

V.R. = `(4d)/d = 4`

(e)

1. There is less weight on pulleys A and B.
2. There's no friction at all between the axle and the pulleys.