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QuestionWhat is the angular velocity of the Earth around the Sun? How do we get it? Asked by: Zahi Assir AnswerCalculating the angular velocity of the Earth is a deceptively easy task. The reason for this is simple - the angular velocity is defined as the angle subtended in a certain time. We know the Earth goes round the Sun, all the way around is 2 radians (360 degrees). We also know that it takes a year (approx 365 days) which is therefore about 3.2x10 ^{7} secs.
Therefore = 2 / 3.2x10 ^{7} = 2.0x10^{-7} rad/s. We have calculated the angular velocity.
However, if we can measure the distance to the Sun we can also calculate the velocity of the Earth relative to the Sun. Although unless we define a direction this is more technically known as the speed. This can be done by looking at the definition of the radian. The radian is a unit which conects the radius of an arc, the length of the arc and the angle subtended by the arc. The formula for this is s = r x (where s is the length of the arc, r is the radius and the angle). So if we know the radius of the Earth's orbit (1.5x10 ^{11}m) we can substitute the angular velocity from our previous equation
to give v = x r (where v is the velocity, the angular velocity and r the
radius).
So, the Earth travels through space (relative to the Sun) at: v = 2.0x10 ^{-7} x 6.4x10^{6} = 3.0x10^{4}m/sAnswered by: Edward Rayne, Physics Undergraduate Student, Cambridge UK |

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Cool Summer Science Projects

Why not make science a part of your family’s summer? Perhaps you can set aside one day a week for outdoor projects—maybe Mad Scientist Monday or Scientific Saturday? Here are a few ideas to help get you started. Continue reading ...

10 Ways to Keep Your Kids Interested In Science

Young children are natural scientists: they ask questions, pick up sticks and bugs outside, and are curious about the world around them. But as they get a bit older, many kids gradually lose their interest in science. They might see it as just another task at school, something that doesn't apply to their lives. Of course nothing could be further from the truth, so here are ten ways you can remind your kids that science is everywhere. Most of these are fun for adults, too! Continue reading ...

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