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    Help w/Current Through Batteries

    In the figure below, the resistances are R1 = 1.1 , R2 = 1.5 , and the ideal batteries have emfs 1 = 2.0 V, and 2 = 3 = 5.5 V. I feel like I've tried everything to solve this problem; I just don't get it!
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    Linear Momentum of A System of Particles

    At time t = 0, a ball is struck at ground level and sent over level ground. The figure below gives the magnitude p of the ball's momentum versus time t during the flight. (p1 = 7.0 kg·m/s and the vertical axis is marked in increments of 0.5 kg·m/s.) At what initial angle above the horizontal is...
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    Vectors problem trouble

    The two vectors a and b have equal magnitudes of 13.0 m and their angles are θ1 = 30° and θ2 = 100°. Find the components of their vector sum, r. I know this is a very simple problem, but I can't get it! And it is frustrating me to no end. I know the y component of the sum is 16.3. (I...
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    Finding An Initial Speed, Intro to Physics Question

    A boy tosses a coin straight up to 2.8 m. Suppose the height when the coin leaves his hand is 1.2 m. What was the initial speed of the coin when it left his hand? I'm just confused as to what equation to use. And I don't know whether to assume the acceleration is -9.8 m/s^2. Thanks.