chandelier

i was in my living room today, watching my brother play halo 3, when i noticed something about the chandelier that hangs in the living room. It is held by one ornate cord, which has tension because of the force of gravity exerted on the chandelier (which is mass times the acceleration of gravity). The tension in the cord-if it was assumed to have no mass-would have the same amount of force as the force of gravity to keep the chandelier at equilibrium and stay at rest. Unfortunately, in the real world, because everything has mass, the force of the tension in the rope and the force of gravity, although should be very close in number, are not exactly equal.

the great thing about the chandelier is that is also has the property of potential energy. If, for some bizarre reason, the tension in the cord that held the chandelier up broke, the force of gravity would force the chandelier to fall at a negative acceleration 9.8 meters per second. If we measured the height of the chandelier and the mass of the chandelier, we could easily obtain the velocity of the chandelier when it hit the ground because all potential energy would have been converted into kinetic energy (assuming that air resistance is irrelevant and no work is added into the system).

that's my physics epiphany for the day. ☺ see ya in a few weeks.

walking up stairs

Late tonight, my brother decided to walk up the stairs to my sister's room because he needed to give my sister a remote control for the television. When he picked up the remote control, he added energy to it (potential energy = mg x height). No work was done to the remote when he was walking around on a flat surface (work requires that there is force and a movement in the same direction as the force exerted on the object), but when he reached the stair case, work was exerted onto the remote control (because the vertical force he is exerting to keep the remote control in the air is now moving in a vertical motion).

One may wonder how my brother could be moving in a vertical motion even though my brother is not going straight upward. This is because his movement (which is diagonal) can be split into vectors. When splitting the movement into vectors, there are two components: a vertical force and a horizontal force. To find the magnitude of the vertical component, one would multiply the magnitude of the overall vector with the sine of the angle of the force.

How amazing it is that my brother walking up and down stairs can trigger Physics thoughts!