Question

why is a jack screw provided with a long arm

Answer 1

Jack screw is provided with a long arm so that the distance between the line of action of force (that is where the force is applied) and the point where the jack screw is connected to the object is as large as possible.. And hence larger the distance between the two mentioned above, larger will the force produced.. Making the work easier..

Hope it helped..

Answer 2

A jack screw is provided with a long arm in order to have the effort less than the load. Therefore, the long arm of the jack screw, the more force it can apply.