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    Projectile motion - Finding velocity (not given time or angle)

    Homework Statement A baseball is hit so that it reaches a maximum height of 20.0m and travels 90.0m before hitting the ground. With what velocity is the ball hit? The Attempt at a Solution I'm confused, i went into trying to find the time but i couldn't without a given angle. I went to say...
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    Projectile motion

    Homework Statement A ball is kicked at a velocity of 40.0 ms at 60 degrees above the horizontal/ a) When is the ball 25.0m above the ground? The Attempt at a Solution First i broke them down into there x and y components but having problems on the (25.0m) part. I did Vix = 40 cos 60 = 20...
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    Calculating minimum force

    1. A 1 tonne rock is being dragged up a 30 degree slope using the a pulley system. If there is a constant resistance to movement between the rock and the ground of 350N, calculate the minimum force necessary to drag the rock up the slope. 2. 3. All i got so far is 1t = 1000kg...
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    Solar Luminosity

    In a question is says that Brightness = Luminosity/4πr₂ (for a star). Procyon = 7L☉ and 11.41 light years as distance. the equation in B= 7L☉/ 4π(11.41)₂ the answer turned out to be 0.004 L☉ watts per square light year (its a textbook question). What i don't understand is what is 7L☉...