Newton’s 2nd law of motion – Definition, Examples, FAQ
We know that momentum is defined as the product of mass and velocity of body. Hence, p= mv. SI unit of momentum is kg.m/s.
When there is change in momentum of body, force associated with it also changes, which was predicted by Sir Newton and stated in his law stated as,
‘Rate of change of momentum is directly proportional to the impressed force, and the change in momentum is takes towards the direction of applied force.’
This law is very important in understanding the mathematical form of force with which we can find the magnitude of force acting on the body.
Suppose the object of mass ‘m’ change velocity from v1 to v2, so that the momentum changes from p1= mv1 to p2= mv2.
Then according to Newton’s 2nd law
∆P = p2 – p1
∆P = mv2 – mv1
∆P = m (v2 – v1)………………….(1)
According to second law of motion, we can have,
F α rate of change of momentum
F α (change of momentum)/time
Important FAQ
Q.1) What is the difference with weight and force?
Answer: Weight is the gravitational force exerted by earth on object. According to Newton’s law, the formula for weight is written as,
W =m.g (Where ‘g’ is acceleration due to gravity)
Q.2) What is impulse?
Answer: Product of force and time is called as impulse.
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