K.C.S.E Physics Q & A - MODEL 2005PP2QN02

K.C.S.E Physics Q & A - MODEL 2005PP2QN02

​ a) Fig 2. Shows a wheel and axle being used to raise a load W by applying an effort F The radius of the large wheel is R and of the small wheel r as shown.

​(i) Shows that the velocity ratio (V.R) of this machine is given by R/r
(ii) Given that r= 5cm, r=8cm, determine effort required to raise a load of 20N if the efficiency of the machine is 80% 
(iii) It is observed that the efficiency of the machine increases when it is used to lift large loads. Give a reason for this.

answers