• Question: Why do objects fall at the same speeds ? Can you explain the law of falling bodies ?

    Asked by shanman to Angela, Karen, Shane on 21 Nov 2013.
    • Photo: Karen McCarthy

      Karen McCarthy answered on 21 Nov 2013:

      Good question Shanman. Well firstly lets look at the law of falling bodies :
      A falling body in a vacuum accelerates at the rate of 32 feet, per second (9.8 m/s) during each second that it falls. This acceleration is called the acceleration of gravity, which is expressed mathematically as g. (In air, the body accelerates until it reaches its terminal velocitya constant velocity at which air resistance equals the force of gravity.)

      Basically this means that any falling objects all move downward under the influence of gravity (and because gravity is everywhere on Earth it affects every fall). This means that a bullet shot down toward the ground falls at the same speed as a bullet dropped toward the ground. This is due to the effect of gravity on an object.

      Objects of different masses or densities appear to defy this law, for example a lump of lead vs a bunch of feathers but this is due to air resistance. In a vacuum, both these objects would continue to fall and land together, regardless.

    • Photo: Angela Stevenson

      Angela Stevenson answered on 21 Nov 2013:

      Hi Shanman, excellent question! In the 17th century, when Galileo proposed the law of falling bodies. It states that a falling body in a vacuum accelerates at the rate of 32 ft/s (9.8 m/s) during each second that it falls. This acceleration is called the acceleration of gravity, which is expressed mathematically as ‘g’. He showed that the rate of fall caused by gravity is the same for all objects and did this by rolling balls down a sloping board and determined the rate at which they accelerated as they fell. But then it’s a bit contradictory that a lump of lead will fall faster than a feather or leaf. These objects fall at a different rate because of air resistance, but put them in a vacuum, and the lump of lead, the feather, and leaf will all fall at the same rate. This phenomenon was demonstrated by astronauts on the moon, which has no atmosphere (like here on Earth). Hope that helps!

    • Photo: Shane Mc Guinness

      Shane Mc Guinness answered on 21 Nov 2013:

      nice answers guys. Though Karen, a bullet shot towards the ground falls A LOT faster than one dropped. However, one shot horizontally across the ground falls at the same speed as one dropped.

      (p.s. if people are copying and pasting from http://www.howstuffworks.com/falling-bodies-info.htm , please correct the typos at least….!)

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