Question

physical significance of momentum

Answer 1

@pofp, If you don't know the answer, writing "I don't know" is really a waste of everyone's time.

Also, you wrote the wrong definition. Momentum is defined as the product of an object's mass \( m \) times its velocity \( v \) where \( v \) is a vector,
\[ p = mv \]
and hence momentum itself is a vector.

Clearly just using the definition you can get a sense of what it means. If a cat and a dog are both running at v = 2 m/s east, but the dog weighs twice as much as the cat, then the dog has twice the momentum. So for example, if both experience a force in the form of a strong wind that blows west, it will take that force twice as long to stop the dog as it would the cat.

A force /( F /) applied for a period of time \( t \) is called an impulse \( I \), and we write
\[ I = Ft \]
You can see mathematically that this must be equal to change in momentum as follows. By definition, acceleration \( a \) is change in velocity,
\[ a = \frac{v_2 - v_1}{t} \]
Hence
\[ I = Ft \]
\[ = (ma)t \ \ \ \hbox{ by Newton's second law} \]
\[ = m(at) \]
\[ = m(v_2 - v_1) \ \ \hbox{ by definition of acceleration } \]
\[ = mv_2 - mv_1 \]
\[ = p_2 - p_1 \]

Answer 2

What is incredibly useful about this is it helps us analyze the interaction of two or more bodies that may collide with each other. You can see from what we just wrote down that momentum can only change if there is a force acting. That means that the combined momentum of two or more bodies does not change unless there is an external force acting on that system of particles.

If you're interested in a meater exposition of this topic, watch this great lecture:
http://ocw.mit.edu/courses/physics/8-01-physics-i-classical-mechanics-fall-1999/video-lectures/lecture-15/

Answer 3

Momentum:
take an example ,A running cycle(with velocity v) dashes against a boy and A running truck (with also velocity v)dashes against the boy.in which case boy hurts more.....what's the answer? the answer will be in the case of truck..why? the answer will be that the truck has more momentum than cycle...this is significance of momentum.here cycle has less mass than truck..
the liner momentum=mass*velocity and it lies along the direction of velocity.It is vector quantity..

Answer 4

From the 2nd law of motion :
the rate of change in linear momentum gives you the Force.
P=m*V...P is linear momentum
differentiate both side with respect to time:
dP/dt=m*dV/dt=m*a=F