Respuesta :

Answer: 1. flying a plane (friction between air and plane)

2. ice skating (friction between ice and skate blade)

3. swimming (water & skin)

4. rowing a boat (water and boat)

             or

1).  between parts of machine during Relative motion

2).  Rowing a boat in water

3). moving heavy mass on the surface

4).  Flying of aeroplane

5).  Transfer of liquid through pipe

Explanation: As we know that friction resist the relative motion of two surface with respect to each other.

So here we require less friction in all above cases as we would like to transfer surface on another surface

so here in order to reduce the friction we need to decrease the value of coefficient of friction.

Hope this helps........ Stay safe and have a Merry Christmas!!!!!! :D

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