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  1. C

    Spring pull question

    1. The left end of a spring is attached to a wall, When Bob pulls on the right end with a 200N force, he stretches the spring my 20cm. The same spring is then used for a tug-of-war between Bob and Carlos. Each pulls on his end of the spring with a 200N force. How far does Bob's end of the spring...
  2. C

    Conservation of Energy and ball problem

    [b]1.Ball 1 with an initial speed of 14 m/s has a perfectly elastic collision with Ball 2 that is initially at rest. Afterward, the speed of Ball 2 is 21 m/s. What will be the speed of Ball 2 if the mass of Ball 1 is doubled. [b]2. conservation of momentum: m1(v1i)=m1(v1f)+m2(v2f)...
  3. C

    Force, Torque and Angular Acceleration Problem

    [b]1. A man sharpens a knife by pushing it against the rim of a grindstone. The 30-cm diameter stone is spinning at 200 rpm and has a mass of 28 kg. The coefficient of kinetic friction between the knife and the stone is 0.20. If the stone loses 10 % of its speed in 10s of grinding, what is the...
  4. C

    Angular Momentum/Impulse Problem

    [b]1. A 1.8 kg, 20 cm diameter turntable rotates at 160 rpm on frictionless bearings. Two 500 g blocks fall from above, hit the turntable simultaneously at opposite ends of a diagonal, and stick. What is the turntable's angular velocity, in rpm, just after this event? [b]2. Angular...
  5. C

    Torque, Rotation, Pulley problem

    [b]1. A 2.5 kg block and a 1.5 kg block are attached to opposite ends of a light rope. The rope hangs over a solid frictionless pulley that is 30 cm in diameter and has a mass of .75 kg. When the blocks are released, what is the acceleration of the lighter block. Ok, the book says 2.2m/s^2...
  6. C

    Gravitational torque about a point on a rod

    [b]1. A 2.0 kg uniform, horizontal rod is 1 m in length. What is the gravitational torque about the point A that is 25 cm from the left end of the rod. [b]2. T=Fr F=mg T=mgr [b]3. The center of gravity of the rod is directy at its center, so is therefore 25 cm from the...