G495 Advance Notice Article June 11th 2012
Physics exam discussion - share revision tips in preparation for GCSE, A Level and other physics exams and discuss how they went afterwards.
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Re: G495 Advance Notice Article June 11th 2012I read your whole conversation and don't get it at all - the mass must be moving too, right? So it can't be used as a fixed point to measure movement of the ground ...(Original post by cadaverous)
OH I GET IT NOW! THANK YOU EVER SO MUCH!! XD
So basically the frame is fixed but the boom is hinged to the frame. When the frame moves in the same direction of the ground, the mass on the boom would want to swing. But we are only interested in the displacement of the ground/frame in relation to a fixed mass, so the mass is damped to reduce the unwanted swinging.
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Re: G495 Advance Notice Article June 11th 2012Wow, you're up at 3??? Anyways, the mass doesn't move, what actually happens is when there is an earthquake the frame moves with the ground, because its attached to it (but you knew that), because the mass is heavy and so has inertia (resistance to motion) it doesn't move with the frame. Imagine holding the mass in one place with your hands and instead the you moved the frame. That's whats happening, we measure the distance and speed the frame and so ground moves relative to the mass.(Original post by joker12345)
I read your whole conversation and don't get it at all - the mass must be moving too, right? So it can't be used as a fixed point to measure movement of the ground ... -
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Re: G495 Advance Notice Article June 11th 2012exactly what he said.(Original post by kauymatty)
Wow, you're up at 3??? Anyways, the mass doesn't move, what actually happens is when there is an earthquake the frame moves with the ground, because its attached to it (but you knew that), because the mass is heavy and so has inertia (resistance to motion) it doesn't move with the frame. Imagine holding the mass in one place with your hands and instead the you moved the frame. That's whats happening, we measure the distance and speed the frame and so ground moves relative to the mass.
the mass must be stationary, and everything else must move relative to the mass. now the frame happens to be one of the things that oscillates relative the mass, which actually enables us to measure earthquakes. if the system resonated, the mass will start oscillating as well, which is not what we want
Last edited by Dhanu123; 11-06-2012 at 10:54.
