For each of the following forces, what is the equal and opposite force required by Newton's Third law?

Question

a) the force of gravity pulling down on a book?
b)The force of a helicopter blade pushing down on the air?
c) the force of a hammer on a nail?
d)the force of air resistance acting on a thrown baseball?

Answer 1

a) The force of the earth's gravity pulling down on the book is the opposite of the book's force of gravity pulling up on the earth. No joke. (Note, the relative accelerations are much different mb<< b) The force of the air pushing upward on the helicopter.
c) The force of the nail on the hammer (why the hammer stops).
d) The force of the baseball on the air--although this results more in heat than a coherent motion of the atmosphere.

Answer 2

(1) Normal reaction offered by the plain where the book is kept.
(2) The lifting force of the helicopter.
(3) The frictional force of wood or the wall where the nail is being hammered.
(4) The forward force of the base ball

Answer 3

a, it falls freely, or a desk or table stops it by applying equal force
b.the force with which the helicopter moves up
c,the nail goes into the plank with equal and opposite force
d,base ball slows down with equivalent force acting on it in oppt direction

Answer 4

a) normal force.....Fn
b)?
c) force (input)
d) force of friction

hope this helps you somewhat.