Recent content by srhly

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    Calculate the resistance, then find the current at the new voltage

    A 78.9 W, 107.3 V light bulb is plugged into a 59.2 V outlet. If energy costs 4.9 cents/kW*h, how much does it cost per month (30 days) to leave the light bulb turned on? Answer in units of cents. This is what I did: (78.9W/107.3V)(59.2V)(24hours)(30days)(4.9cents/kW*h)(1kW/1000W) I...
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    Calculating Work Required to Remove Dielectric Slab from Charged Capacitor

    An isolated capacitor has a dielectric slab k between its two plates. The capacitor is charged by a battery. After the capacitor is charged, the battery is removed. The dielectric slab is then removed. Finally, the capacitor reaches equilibrium. Initially the parallel-plate capacitor has a...
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    Electric Potential V at Point P: Multiple Choice

    Can anybody help me on this question, I'm stuck. I have a picture attached for clarification. Consider two concentric spherical conducting shells. O is at the center of the shells. THe inner shell has radius a and charge q1 on it, while the outer shell has radius b=3a and charge q2 on it...
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    Calculating Kinetic Energy of Particle B Using Electrical Potential

    Particles A (of mass m and charge Q) and B (of mass m and charge 5 Q) are released from rest with the distance between them equal to 0.4939 m. If Q= 31 uC, what is the kinetic energy of particle B at the instant when the particles are 2.4939 m apart? Answer in units of J. I know that the...
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    Proton Vertical Displacement in Electric Field

    A proton has an initial velocity of 9.4x10^6 m/s in the horizontal direction. It enters a uniform electric field of 28800 N/C directed vertically. What is the vertical displacement of the proton after the electric field acts on it for 7.1202 ns, the time it takes the proton to travel 0.067 m...
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    Number of electrons on charged sphere

    Can anyone help me with this question. A sphere is charged with electrons to -5x10^-6 C. The charge of an electron is -1.6x10^-19 C. How many electrons are there on the sphere?
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    Siren Wavelength for Car Travelling North at 29.4 m/s

    An ambulance is traveling North at 64.1 m/s, approaching a car that is also traveling North at 29.4 m/s. The ambulance driver hears his siren at a frequency of 705 cycles/s. The velocity of sound is 343 m/s. What is the wavelength at the car driver's position for the sound from the...
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    Find Volume of Metal Object: 860-785 N, 9.8 m/s^2

    A metal object is suspended from a spring scale. The scale reads 860 N when the object is suspended in air, and 785 N when the object is completely submerged in water. The acceleration due to gravity is 9.8 m/s^2. Find the volume of the object. Answer in m^3.
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    Finding Friction Force in a 11 kg Sphere

    Sorry, I tried to post a picture that helped explain but it didn't work. F is the tension force of the string and the 62 degree angle is relative to the horizontal.
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    Finding Friction Force in a 11 kg Sphere

    I wasn't for sure where to start with this problem. It is the first of 3 so if I understand how to do this one, I will be able to most likely get the others. I'm pretty sure that I need to make a free-body diagram of the forces in this situation but wasn't for sure where to label the friction...
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    Solving Question: Speed of Ball with Rigid Cannon

    I had a two-part question but I've figured out the first part. A cannon with mass of 1960 kg fires a 24.5 kg ball horizontally. The cannonball has a speed of 120 m/s after it has left the barrel. For the first part I found that if the cannon was free to roll horizontally, its speed...
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    Multiple choice ? on center of mass

    Two balls of masses m1 and m2 are moving along x-axis w/ velocities, v1>v2>0. After transforming from the lab frame to the center-of-mass frame, what are the velocities of m1, v1com, and mass m2, v2com? Vcom is the center of mass velocity for the system of both balls. The choices are...
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    Getting wrong answer on physics problem

    A bead slides without friction around a loop-the-loop. The bead is released from height of 25.1m from the bottom of the loop-the-loop which has a radius of 9m. THe acceleration due to gravity is 9.8 m/s^2. There is a point A at the very top of the loop. I need to know the normal force(Fn) at...
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    What is the critical angle for a sliding box on a spherical dome?

    I have several problems like this and am confused at how to solve. A small box of mass 9 g is initially at some angle with respect to the ploar axis of a spherical dome of radius 3 m as shown in the figure. Starting from rest, the box slides down along the frictionless spherical surface. The...
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