lecture13

# lecture13 - Phys 2101 Gabriela Gonzlez dP dL F= ; = dt dt...

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Phys 2101 Gabriela González

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2 Not a new concept! Bodies in equilibrium don’t move, so they don’t have linear momentum or angular momentum. Therefore, the net force and the net torque (about any point, in all directions!) must be zero. Penguin 1 has M=48kg; strings are at ¼ of the rod lengths from the left; crossbars are massless. What are the masses of the other penguins? F = d P dt ; τ = d L dt
3 In principle, there are six equilibrium equations: three components of the net force F x , F y , F z ; and three components of the net torque, τ x , τ y , τ z. If the motion is restricted to the xy plane, then there are only three equations: two components of the force, F x , F y ; and one component of the torque, τ z. However, the torque can be calculated about different points. m=1.8 kg, M=2.7 kg. What do the scales read?

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4 Some special forces: Gravity always acts on the “center of gravity”=“center of mass”. Walls exert
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## This note was uploaded on 12/01/2011 for the course PHYS 2101 taught by Professor Grouptest during the Fall '07 term at LSU.

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lecture13 - Phys 2101 Gabriela Gonzlez dP dL F= ; = dt dt...

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