What is negative work? Derive the expression for kinetic energy.
Answers
Answer:
NEGATIVE WORK: The work done is said to be negative work when force and displacement are in opposite direction. Example: When an object is thrown upwards,the force of gravity is in downward direction whereas displacement acts in upward direction.
Explanation:
Kinetic Energy:
The energy possessed by an object due to its motion is called as kinetic energy.
Derivation:
Let us consider an object of mass "m" which is at rest on smooth horizontal plane.
Let a Force ,F acts on the object and let the object from rest moves from point A to point B and covers a displacement S.
The Work done by Force on the object is :
Workdone = Force x displacement.
W=F×S ____(1).
From third equation of motion;
V
2
−U
2
=2aS
S=
2a
V
2
−U
2
______(2)
By Newtons second law of motion:
F=ma
From equation 1 and 2
W=
2a
m∗a∗(V
2
−U
2
)
As we have assumed object is at rest, U=0
W=
2
mV
2
The Work Done appears as kinetic energy of the body.
Therefore,
K.E=(
2
1
)mV
2