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  1. U

    Rotational Kinematics & Energy

    A 10.7 g CD with a radius of 6.06 cm rotates with an angular speed of 30.9 rad/s. What is its kinetic energy? What angular speed must the CD have if its kinetic energy is to be doubled? Here is my work: kinetic energy energy = 1/2 m v2 = 1/2 m ( r ω )2...
  2. U

    Potential Energy & Conservative Forces #20

    Two blocks, each with a mass m = 0.348 kg, can slide without friction on a horizontal surface. Initially, block 1 is in motion with a speed v = 1.56 m/s; block 2 is at rest. When block 1 collides with block 2, a spring bumper on block 1 is compressed. Maximum compression of the spring occurs...
  3. U

    Potential Energy & Conservative Forces #21

    In the figure below a 1.24 kg block is held at rest against a spring with a force constant k = 700 N/m. Initially, the spring is compressed a distance d. When the block is released it slides across a surface that is frictionless, except for a section of width x = 4.85 cm that has a...
  4. U

    Potential Energy & Conservative Forces #18

    A skateboard track has the form of a circular arc with a 4.00 m radius, extending to an angle of 90.0° relative to the vertical on either side of the lowest point, as shown in the figure below. A 55.9 kg skateboarder starts from rest at the top of the circular arc. What is the normal force...
  5. U

    Work & kinetic energy problem

    The human brain consumes about 21.9 W of power under normal conditions, though more power may be required during exams. How long can one Snickers bar (280 cal per bar) power the normally functioning brain?[/B] (Note: The nutritional calorie, 1 Cal, is equivalent to 1000 calories (1000 cal) as...
  6. U

    One-Dimensional Kinematics Problem

    Hey guys, There is one more question I am having a problem with. Here it is: You jump from the top of a boulder to the ground 2.07 m below. Calculate your deceleration on landing. Assume that in order to soften your landing, your legs will bend 0.510 m. Give your answer in units of g. Do...
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    One-Dimensional Kinematics Problem

    Hey guys, I just joined and I have a question. Here is my problem: Sitting in a second-story apartment, a physicist notices a ball moving straight upward just outside her window. The ball is visible 0.291 s as it moves a distance of 1.22 m from the bottom to the top of the window. What is...
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