The figure shows a wheel and axle being used to raise a load W by applying an effort F. the radius of the large wheel...

The figure 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 machines increases when it is used to lift large loads. Give a reason for this.

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(iii) When the load is large the effect of friction and weight of the moving parts is negligible.
NB: Friction and weight of moving parts to be mentioned.

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sharon kalunda answered the question on September 10, 2019 at 10:29

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