Question

define kinetic energy and derwe expression for kinetic energy
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Answer 1

Answer:

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Explanation:

In physics, the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes.Translational kinetic energy of a body is equal to one-half the product of its mass, m, and the square of its velocity, v, or 1/2mv2.

Answer 2

Answer:

(a) Energy possessed by a body by virtue of its motion is kinetic energy.

Derivation:

Consider a body of mass m initially at rest. If on application of force F, it travels a distance s, then

Work done, W = F x s

By Newton's second law, F = ma

W = ma x s

where, a = acceleration

 

Using equation of motion v2 - u2 =2as, we get

(v2-u2)/2 = as

W = m x (v2 - u2)/2

As intial velocity is zero, W =  ½mv2

This work done is stored as kinetic energy of the object.

So, KE = ½  mv2

 

 

Let the mass of lighter object be m1 and that of heavier object be m2.

m1< m2

p1 = p2

For a given momentum, KE 1/m

So  

Since , so lighter object has larger kinetic energy.