Answer:
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
Step-by-step 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
Here we know that friction force is given as

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