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How To: Understand The Law Of Conservation Of Energy

The law of conservation of energy can be difficult to understand. Fear not, A Moment of Science is here to help!

energy150

Photo: JAS_photo (Flickr)

The law of conservation of energy is simple to understand once you take the time to explore it.

There’s a rule in physics called the law of the conservation of energy. Energy can neither be created out of nothing, nor disappear into nothing — all it does is change forms. That sounds simple, but it confused people for a long time.

Energy Is Lost

To see why, let’s think of an easy example, and then a harder one. You roll an eight ball across a billiard table. When it hits the cue ball, the cue ball starts moving and the eight ball stops.

Why? Because the kinetic energy you put into the eight ball with your hand has been passed into the cue ball. Notice that no energy is lost, it just traded places.

Changing Forms

Okay, that was easy. Now suppose you see a car going down the street at a constant speed. Suddenly the driver slams on the brakes. The car comes to a halt. Where did the energy go?

Unlike the eight ball situation, the energy seems to have vanished! In fact, we now know that the energy merely changed forms.

Kinetic to Sound

When the driver hit the brakes, what else happened?

For one thing, there was a loud screeching noise. That’s kinetic energy being converted into sound waves.

The brakes and the skidding tires became hot. That’s kinetic energy being converted into heat. Pebbles were knocked out of the way. That’s a mini-version of the billiard balls — kinetic energy being passed from one object to another.

Energy Can Change Forms, But Can’t Disappear

All these little outlets add up to exactly as much kinetic energy as the car had in the first place. It works out just the way the law of the conservation of energy says: energy can change forms, but can’t ever disappear.

  • Anonymous

    remember kinetic energy can also be used to produce renewable energy such as electric.
    Buddy T
    Owner of – kinetic energy

  • http://www.hi.com/ Jyc

    Science

  • http://www.hi.com/ Jyc

    Science science

  • http://www.hi.com/ Jyc

    Science science science

  • http://www.hi.com/ Jyc

    O_O -… So this was posted 4 years ago?

  • http://www.hi.com/ Jyc

    Photo: JAS_photo (Flickr)
    The law of conservation of energy is simple to understand once you take the time to explore it.

    There’s a rule in physics called the law of the conservation of energy. Energy can neither be created out of nothing, nor disappear into nothing — all it does is change forms. That sounds simple, but it confused people for a long time.

    Energy Is Lost

    To see why, let’s think of an easy example, and then a harder one. You roll an eight ball across a billiard table. When it hits the cue ball, the cue ball starts moving and the eight ball stops.

    Why? Because the kinetic energy you put into the eight ball with your hand has been passed into the cue ball. Notice that no energy is lost, it just traded places.

    Changing Forms

    Okay, that was easy. Now suppose you see a car going down the street at a constant speed. Suddenly the driver slams on the brakes. The car comes to a halt. Where did the energy go?

    Unlike the eight ball situation, the energy seems to have vanished! In fact, we now know that the energy merely changed forms.

    Kinetic to Sound

    When the driver hit the brakes, what else happened?

    For one thing, there was a loud screeching noise. That’s kinetic energy being converted into sound waves.

    The brakes and the skidding tires became hot. That’s kinetic energy being converted into heat. Pebbles were knocked out of the way. That’s a mini-version of the billiard balls — kinetic energy being passed from one object to another.

    Energy Can Change Forms, But Can’t Disappear

    All these little outlets add up to exactly as much kinetic energy as the car had in the first place. It works out just the way the law of the conservation of energy says: energy can change forms, but can’t ever disappear.

  • http://www.hi.com/ Jyc

    Screeeech!

  • http://www.hi.com/ Jyc

    O_O

  • http://www.hi.com/ Jyc

    あなたはワッフルが好きですか?はい、私たちはワッフルが好き!あなたはパンケーキが好きですか?はい、私たちはパンケーキが好きです!あなたはフレンチトーストが好きですか?はい、我々はフレンチトーストが好き!斗ダダ斗は、口がいっぱいに得るために待つことができない!ワッフル!

  • http://www.hi.com/ Jyc

    Pinkie pie is cool!

  • http://www.hi.com/ Jyc

    It must suck to be energy. It’s always moving around. It never has time to sit and play Smash Bros or Kirby’s Nightmare in Dreamland Wii…

  • http://www.hi.com/ Jyc

    Jyc is cool!

  • http://www.hi.com/ Jyc

    I like this website! I found a post about what makes meat tender! Mmmm… Meat.

  • http://www.hi.com/ Jyc

    Mmm… I still like meat!

  • http://www.hi.com/ Jyc

    I feel ya. It wouldn’t be able to play Kirby Triple Deluxe, either.

  • http://www.hi.com/ Jyc

    Yeah… That would suck.

  • http://www.hi.com/ Jyc

    Hi

  • http://www.hi.com/ Jyc

    I try to leave this page, but I always come back because it is so interesting.

  • http://www.hi.com/ Jyc

    Why the O_O face?

  • http://www.hi.com/ Jyc

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    How To: Understand The Law Of Conservation Of Energy
    By WILLIAM OREM
    Posted July 29, 2010

    The law of conservation of energy can be difficult to understand. Fear not, A Moment of Science is here to help!

    Listen Now: How To: Understand The Law Of Conservation Of Energy0:00

    Photo: JAS_photo (Flickr)
    The law of conservation of energy is simple to understand once you take the time to explore it.

    There’s a rule in physics called the law of the conservation of energy. Energy can neither be created out of nothing, nor disappear into nothing — all it does is change forms. That sounds simple, but it confused people for a long time.

    Energy Is Lost

    To see why, let’s think of an easy example, and then a harder one. You roll an eight ball across a billiard table. When it hits the cue ball, the cue ball starts moving and the eight ball stops.

    Why? Because the kinetic energy you put into the eight ball with your hand has been passed into the cue ball. Notice that no energy is lost, it just traded places.

    Changing Forms

    Okay, that was easy. Now suppose you see a car going down the street at a constant speed. Suddenly the driver slams on the brakes. The car comes to a halt. Where did the energy go?

    Unlike the eight ball situation, the energy seems to have vanished! In fact, we now know that the energy merely changed forms.

    Kinetic to Sound

    When the driver hit the brakes, what else happened?

    For one thing, there was a loud screeching noise. That’s kinetic energy being converted into sound waves.

    The brakes and the skidding tires became hot. That’s kinetic energy being converted into heat. Pebbles were knocked out of the way. That’s a mini-version of the billiard balls — kinetic energy being passed from one object to another.

    Energy Can Change Forms, But Can’t Disappear

    All these little outlets add up to exactly as much kinetic energy as the car had in the first place. It works out just the way the law of the conservation of energy says: energy can change forms, but can’t ever disappear.

    Tags

    billiard balls, energy, kinetic energy, the law of the conservation of energy
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  • http://www.hi.com/ Jyc

    Can someone please translate this?

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