16. Answer Breifly VI

 

This is because resulatant forceuniform motionturning effect to tighten the screws depends upon the distance of the applied forceperpendicular distance of the applied forceaverage distance of the applied force from the axis of rotation is power arm. LargerLesser the power arm less is the force required to turn the screws. So spanner is provided with a long handle.

2. While catching a cricket ball the fielder lowers his hands backwards. Why?

 

When the fielder lowers his hands backwards, he reducesincreases the value of time of collision and so retardation is decreasedincreased. Hence retarding force becomes than higherlesser  before and the palm of the fielder is not hurt very much.