what is kinetic energy? derive the relation for kinetic energy of a body which start from rest and then moves with velocity 'V' with mass of a body 'M'? class 9 science
Answers
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=F
net
×S-------(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×(V
2
−u
2
/2a)=(1/2)m(V
2
−u
2
)
As we assumed object at rest, u=0
W=(1/2)mV
2
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=1/2mV
Answer:
Kinetic energy of an object is the measure of the work an object can do by virtue of its motion.
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