Question

Define kinetic energy and write in expression for k.E derive it​

Answer 1

Answer:

As we assumed object at rest, u=0. W=(1/2)mV2. we know that the kinetic energy of a body moving with a certain velocity is equal to work done on the object to acquire that velocity from rest. ∴K. E=1/2mV2.

Answer 2

Answer:

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.

Derivation:

Let us consider an object of m which is at rest lying on a table.

Let A force F acts on the object which moves the object through a distance S.

The workdone = F × S

W=Force × Displacement -------(1)

Let the work done on the object causes a change in its velocity from u to V and let a be the acceleration.

From Third equation of motion:

V²−u²=2as

s = V² − u²/2a ---------(2)

By Newton's Second law:

F = ma ------(3)

From equation (1), (2) and (3)

W = ma × (V² −u² /2a) = (1/2)m (V² - u² )

As we assumed object at rest, u = 0

W = (1/2)m V²

we know that the kinetic energy of a body moving with a certain velocity is equal to work done on the object to acquire that velocity from rest.

∴K.E = 1/2mV²