Sagdullin F.R. – KSTU student (gr.GD-15-5) Supervisor – Igembekova A.Z.
FORCE
What is force? Do the spring balance and the equal arm balance measure the same thing?
How can we walk on the road? What keeps the planets in their orbits? Why do moving objects slow down? Where can we be weightless? What is moment arm?
All this questions will be answered in the following chapter.
Lifting a hammer, stretching a spring, opening a door, lifting weights, pushing a diskette into a driver or kicking a football are all examples of forces being used.
A force is either a push or a pull that acts on an object.
Whenever you bend, twist, stretch or compress something you are using a pushing or pulling force. A force cannot be seen and described like an object, but the effects of it on different objects can be seen. We can not see the wind but we can see a windmill turning, a yacht moving, a tree bending or a kite flying.
A force can
a) Cause body which is at rest to move;
b) Change the speed or direction of motion of a moving body;
c) Change the shape of size of a body
The ability of a force to change the speed of an object is very useful; an engine increases the speed of a car a parachute slows down a falling object, a jet engine pushes a plane forwards, a gun fires a bullet to a target.
Force always occurs in pairs acting in opposite directions. This was first noticed by Sir Isaac Newton, and he called these forces action and reaction. If a man pulls a rope tied to a wall, the rope also pulls the man, the rope reacts to the man’s action. The book lying on a table exerts a downward force, the table compensates it by an equal and opposite upward force. When a girls sits on a chair, her weight presses down, the chair balances the girl’s downward force by an equal upward force.