A girl and her skateboard have a combined mass of 28 kg and a speed fo 3 m/s. Her mother stands on the sidewalk and hands the girl a 2 kg backpack as she passes by. What is her final speed?

Unlike the idealized voltmeter, a real voltmeter has a resistance that is not infinitely large. a voltmeter with resistance rv is connected across the terminals of a battery of emf e and internal resistance r. find the potential difference vmeter measured by the voltmeter. what is vmeter?