PHYS 6A Midterm: Physics 6A Practice Midterm2 solutions
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PHYS 6A Full Course Notes
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Practice midterm #2 solutions: a locomotive engine of mass m is attached to 5 train cars, each of mass m. the engine produces a constant force that moves the train forward at acceleration a. We just use newton"s 2nd law here: net force = (total mass) x (acceleration) Initially, the total mass is 6m (5 cars, plus the engine) After removing 3 cars the total mass is 3m (2 cars, plus the engine) In both cases the net force is the same (the engine didn"t change). Another way to think about this one is that since the mass is cut in half, the acceleration must double: two boxes are placed next to each other on a smooth flat surface. Box a has mass 1 kg and box b has mass 3 kg. A constant horizontal force of 8 n is applied to box a. Now we do the same thing, but just for box b:
