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  1. B

    Equipotential planes and electric fields.

    Homework Statement Suppose a uniform electric field of magnitude 115.0 N/C exists in a region of space. How far apart are a pair of equipotential surfaces whose potentials differ by 2.0 V? Homework Equations 1 N/C = 1 V/m The Attempt at a Solution I know 115.0 N/C is the same...
  2. B

    Voltage potential due to 2 charges

    Homework Statement Find the potential at points a and b in the diagram for charges Q1 = +1.60 nC and Q2 = -1.60 nC. I know b is 0 Homework Equations V = kQ/r The Attempt at a Solution I tried this using the equation and got 8.99e9 * [( +1.60e-6 / .05) + ( -1.60e-6 / .15...
  3. B

    Waves frequency and mass?

    Homework Statement The longest "string" (a thick metal wire) on a particular piano is 3.0 m long and has a tension of 300.0 N. It vibrates with a fundamental frequency of 27.4 Hz. What is the total mass of the wire? ( in kg) Homework Equations The only relevant equation I could find is...
  4. B

    Work done by wheel.

    A flywheel of mass 183 kg has an effective radius of 0.63 m (assume the mass is concentrated along a circumference located at the effective radius of the flywheel). (a) What torque is required to bring this wheel from rest to a speed of 120 rpm in a time interval of 34.3 s? (b) How much...
  5. B

    Momentum - Car Crash

    A police officer is investigating the scene of an accident where two cars collided at an intersection. One car with a mass of 1135 kg moving west had collided with a 1300 kg car moving north. The two cars, stuck together, skid at an angle of 30° north of west for a distance of 25 m. The...
  6. B

    Work done by a spring when stretched

    I have a simple problem that i can't seem to get right. An ideal spring has a spring constant k = 22.0 N/m. What is the amount of work that must be done to stretch the spring 0.70 m from its relaxed length? I tried W = (-)1/2 k x^2 = - (.5)(22.0) (.7^2) =...