# Can Kinetic energy ever be negative?

### 21 Answers

- Frank NLv 71 decade agoFavourite answer
As the others said, kinetic energy cannot be negative. However, a change in kinetic energy can. Throw a ball straight up and its kinetic energy decreases to zero at its peak. The ball experienced a negative change to its kinetic energy.

- 5 years ago
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RE:

Can Kinetic energy ever be negative?

Source(s): kinetic energy negative: https://biturl.im/WazLg - WildOtterLv 51 decade ago
Kinetic energy = 1/2 m * v^2

Velocity squared will always be positive (or zero), and mass is always positive, so you can't get a negative value for kinetic energy.

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- openpsychyLv 61 decade ago
Kinetic Energy is acquired by matter when it has motion and velocity and equals 1/2*m*v^2 wheremis mass and v is the velocity. Lets us equate the expression to zero and examine

1/2*m*v^2=0

mass can never be zero

v exists and is real

so the expression can never be zero

- oldprofLv 71 decade ago
KE cannot be negative, but the KE term in an equation can have a negative sign.

For example, in PE = KE (potential energy equals kinetic energy), we can write PE - KE = 0 But that does not mean the kinetic energy is negative, it just means that all the potential energy is converted into kinetic energy so that there is no more energy to expend...it's all spent.

As many have pointed out, KE = 1/2 m v^2; so even if v<0, the square causes the KE to remain positive. Think of PE as sand in a hopper; it stays there until we open the stopcock. Then the sand tumbles out of the hopper and that represents kinetic energy because the sand is moving.

But the sand in the hopper, which is the potential energy, is being used up as the falling sand continues until all the sand in the hopper is gone. PE - KE = 0 indicates the end game when all the sand (potential energy) is used up.

Source(s): Physics and engineering degrees. - 1 decade ago
no...ding dong...remember wht einstein said...mass and energy are consrved......when u place a -ve sign in front of energy(1/2m*v^2)it indicates that enerygy is eliminated which is not possible....(Total Energy=Potential Energy+Kinetic Energy)...kinetic chnges to potential and vice versa accordint to the motion and position of the body in consideration

- 1 decade ago
Everything is possibile:

Well, in our "normal" world, the kinetic energy is always positive, because the equation E= m*v² is always positive.

BUT: we must understand that kinetic energy is always kinetic, no matter what the direction of the object is. But kinetic energy is not only related to the movement. It is also related to the matter.

So, in physics, there is a thing called "anti-matter", which means "negative matter".

In that case, we also speak about negative kinetic energy because in that case the "m" is negative: E= -m*v²

- 1 decade ago
V^2 is alwayas greater than or equal to zero

So KE = 1/ m V^2 is can never be negative