Force
in our daily life , we see many things around us in different condition. a glass on a table is in the position of rest . the glass on the table continues to be lying on the table at the same position until somebody displaces it , for moving it, one has to either lift it. push it or pull it. it shows that to bring a body into a motion from resr, some external agency has to act on the body
similarly, a moving objest can be brought to rest when an external agency is applied to it. for example, a moving ball can be brought to rest by appling an external agency. thus, force is an external agency that change or tends to change the state of a body from rest to motion or motion to rest. in other word, force is defined as to push or pull that may change the position of a body . si unit of force is newton. we use force to do differet types of work. different types of force are used for different purpose.
effect of force
force shows different types of effect on bodies. the main effect of force are as given below
force changes the state of the body from rest to motion or motion to rest
if a book is lying on a desk, it continues to be lying at the same position untill somebody displaces it to another place for moving it, one has to apply force. thus, forece can bring a body in rest to motion
the speed of a rolling ball on a surface gradully decrease and finally it stops. here, the frictional force acts to decrease the speed of the ball. htus, force brings a moving body to rest
force changes the direction of the motion of a body
tie a piece os a stone at one end of a string and its other end is held with a hand. the stone is ehirled in a circle as showm in the figure. clearly, its direction of a motion is changing a every instant. here, the direction of the motion of the atone is changed due to the aplied force on it though the string thus, force changes the directoin of the motion of a body.
force changes the shape and size of a body
when a ballon or a rubber ball is sequeezed, it changes tits shape and size.similatrrly, when a spring or a rubber is stretc. hed, its size is changed due to the applied force thus, force changes the shape and size of a body.
types of force
we cannot do anything without force. in our daily life, we apply force to do various types of works. to open and close a door, to lift a body to a height, to moving a bidy at rest and to stop a running body, etc we need force. force is of various types.
puloling and pushing force
a body at rest comes in motion only when either it is pushed or pulled. similarly, a moving body comes at rest if it is pushed or pulled. thus, the force which pushes or tends to push a bodu is called pushing force. a force which pulls or tends to pull a body is called pulling force.
centripetal force and centrifugal force
we have experienced that when a bus turnd in a curved road, our body bends In the oppositer direction from the centre of the road. it is because of the centrifugalk force. the force which pushes bodies away from the centre is centrifugal force.
while running in a curved road, our body bends towards the centre of that curved road. the force ehich pulls us towards the centre is the centripetal force. that is why, a cyclist bends his body towards the centre of the curved path.
therefore, when a body is moves in a circular path, it is acted upon by a force towards the centre of the path. this force is called centripetal force. the body is also acted by a force which tends to move it away from the centre. this force is called centrifugal force.
magnetic force
we can find that a magnet experst force o another magnet. it is magneic force. like poles of the magnets repel while the unlike pole attracts. a magnet also attracts the magnetic substances like iron, nickel, etc. thus, the force producd by a magnet is called magnetic force.