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(a) Draw a diagram of a pulley system of velocity ratio 4. Calculate its mechanical advantage, if its efficiency is 90%.

(b) Why does a rope walker hold a long pole in his hands? Explain.

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Answer

(a) Diagram of a pulley system of velocity ratio 4 is shown below:

Draw a diagram of a pulley system of velocity ratio 4. Calculate its mechanical advantage, if its efficiency is 90%. Physics Sample Paper Solved ICSE Class 10.

Given,

Efficiency (η) = 90%

Velocity ratio = 4

MA = ?

We know, η=MAVR\eta = \dfrac{\text {MA}}{\text {VR}}

Substituting in the formula above we get,

90100=MA4\dfrac{90}{100} = \dfrac{\text {MA}}{\text {4}}

MA = 0.90 x 4 = 3.6

Hence, MA = 3.6 N

(b) The pole increases the walker's moment of inertia or resistance to rotating and prevents him from falling off the wire, allowing the walker time to correct his position and stay balanced. When he feels he is falling towards right, he shifts the pole towards left and vice versa.

In addition, holding the pole low helps to keep his center of gravity low, and this further increases his ability to balance.

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