Kinetic energy cannot be negative, as mass cannot be negative, and the square of speed yields a non-negative value. When a body is at rest, its kinetic energy is equal to zero. When a body is in motion, it always has positive kinetic energy. Moreover, in terms of physics and physical quantities measurement, negative implies something in the opposite direction. Since kinetic energy, like all other types of energy, is a scalar quantity, it has no direction, so it can never be negative.
Suppose we have a car with a mass m = 1000 and a speed v = 20 m/s. We can calculate the kinetic energy (K.E) of the car using the formula
K.E=1/2mv2
Substituting the given values into the formula,
K.E= 1/2×1000 kg×(20 m/s)2
K.E. = 1/2×1000 kg×400 m2/s2
K.E=500 kg⋅m2/s2
K.E=500 Joules
So, it is mathematically proven that the change in kinetic energy will always have a positive value.