Question

Draw a diagram to show how a single pulley can be used so as to have its ideal MA = 2. Derive an expression between MA, VR and efficiency of a machine.

Answer 1

(i) M. A. = `"Load"/"Effort"`

M.A. = `(2"T")/"T"`

= 2

(ii) Efficiency (η) = `"Work Output"/"Work Input"`

η = `(L xx d_L)/(E xx d_E)`

η = `(L/E) xx ((d_L)/(d_E))`

Since `L/E` = M. A. and `d_E/d_L` = V. R.

η = `M. A. xx 1/V. R.`

M. A. = η × V. R.