Newton's second law of motion
What is Newton's second law of motion?
Before diving into Newton's second law of motion.it is compulsory to know the concept of Force,acceleration and mass.Don't worry, firstly we will understand these concepts and then move forward to the main goal.
What is acceleration?
Acceleration is defined as the rate of change in velocity of a body.in other words how velocity is changing with time.For example.A train is at the state of rest,having zero acceleration because there is no change in velocity but when it starts moving its velocity changes with time and then it gains acceleration.
acceleration=(change in velocity)/time
a=( v−u )/t.
Here a=acceleration
v=final velocity
u=initial velocity)
Force:
Force is an influence which changes the motion of a body.A force can cause an object to change its velocity, and acceleration etc.because force is the vector quantity it means that it has magnitude(Value) and direction.For Example (1)a batsman hit the ball and changes the direction of the ball. (2) When we apply force on the wall the wall will remain at rest.
Mass:
Mass is referred to as the quantity of matter (anything that has volume and mass is classified as matter) present in anybody. In other words, mass is the measure of the total number of atoms present in an object. Its SI unit is a kilogram (kg).
Now its time to focus on the main topic.
Newton's second law of motion:
Newton's second law of motion is defined as the force exerted by an object is directly proportional to the rate of change of its momentum. For a body of mass ‘m’, whose velocity changes from u to v in time t, when force ‘F’ is applied.
F∝ Time Change in momentum
F∝ Change in momentum/time
F∝(mv-mu)/t
F∝m( v−u )/t
We know that a=( v−u )/t
we put in above equation we get
F∝ma
F∝ma is the simplest form of Newton's second law of motion.here mass is kept constant
What is the Relationship between Force and acceleration?
Force is directly related with acceleration .It means that if we increase the Force, acceleration will also increase(here mass will be constant) and if we decrease the Force, acceleration will also decrease(here mass will be constant).For example if we increase force 2 times act on a box,the box will also increase its acceleration 2 times and here mass of the body will keep constant.so it is obvious that force is directly proportional to acceleration of a body if mass is constant.
Relationship between mass and acceleration?
Acceleration is inversely related with mass.so, if we increase the mass of the body, its acceleration will decrease(Here we keep, Force = constant).For example if we double the mass of a body,the acceleration of the body will also decrease two times(Here we keep, Force = constant).so it is clear that force is inversely proportional to the mass if net force is constant.
Keep in mind:resistive forces(the forces which oppose the motion of the body like friction,drag force, viscosity etc) will also be neglected in the second law of motion.
