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prettybird

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  1. prettybird

    Sliding on Socks

    By prettybird,

    I'm sure several of us have ran around the house with socks on and tried to slide on wood or smooth floors. 
    Using what we know about friction, we can see that the equation is the coefficient of friction times the normal force, or mg. Since we are on earth, there is obviously a force from gravity and a person has mass. Therefore, the explanation for this fun trick must lie in the coefficient of friction. Since you can slide a decent distance, the coefficient must be small, therefore causing the whole force from friction to be small as well.
  2. prettybird
    There are several ways in which cars demonstrate physics. For one, when you turn, hit the gas or brake, you can see the property of mass called inertia. Anybody or anything in the car tends to continue traveling in the direction the car was originally going in or stay still if the car was stopped.
    Also, the physics behind tires show how cars move. As the tire spins, it uses the friction between it and the road to push the car forward. This is why in snow or mud, where there is little friction, the car cannot move.
    Finally, the antenna and speakers work together to receive radio waves from the air and transmit them into your car as audible sound waves.
  3. prettybird
    I'm not talking about cannonballs like what you shoot out of a cannon. That's obvious, a huge object is hitting you at a large velocity therefore there's a huge force transferred to your body. 
    I'm talking about the cannonballs you do when you jump into the pool with your friends on a warm summer day. (Which we're all looking forward to after this winter). 
    When you jump into a pool, the water has some amount of surface tension to oppose objects from entering it. When you dive in with your hands out, you break that surface tension before the rest of your body enters, and so only your fingertips feel a force. When you do a cannonball, half of your body feels the force, leaving that stinging feeling.
    This is also the reason why when people fall or jump off bridges, they often say the impact kills them (not drowning) because the surface tension applies such a huge force.
  4. prettybird
    Makeup is one of my biggest interests, however I wake up late a lot of the time and don't have time to put it on. It's fun to be creative and almost create art on your face, and to show it off for a day. 
    The big physics principle behind makeup is trying to combat the force of gravity and using friction to help the makeup apply. 
    All the makeup on your face is applied with some amount of friction helping you out. Whether you're applying lipstick from the tube or using a brush to put on eyeshadow, you're counting on friction to put that stuff on your face.
    You also count on that force of friction to keep your makeup on your face throughout the day. If there was no friction, the makeup would fall right off your face.
    (Below are some selected favorites from my collection which all demonstrate this physics principle. Also, my cat Mia is a diva and had to be in the photo.)

  5. prettybird
    If a tree falls in the forest, and no one is around to hear it, does it make a sound?
    When a ball hits the ground or an axe hits a tree, we can hear a noise signaling this collision. Obviously, sound waves are produced, but where exactly do they come from? 
    When two objects collide, one of two things can happen: an elastic or inelastic collision. In the case of elastic, no kinetic energy is lost. Inelastic, however, involves a loss of kinetic energy. Where does it go?
    Part of it goes to heat, but another part of it causes the sound waves to be produced because they need energy. When two objects collide, the molecules of the object vibrate a little, which in turn vibrates the air molecules, creating a longitudinal wave. 
    So, if a tree falls, it does make a sound because the laws of physics don't stop just because there isn't a human to watch it. 

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