# Search results

1. ### Representing a Cardioid

Homework Statement Show that the cardioid r=a(1+cos(theta)) can be represented by r=2acos2(theta/2), 0<=theta<=2pi (theta is between 0 and 2pi). Homework Equations The Attempt at a Solution I'm pretty sure I have to equate the two expressions, but I haven't been able to do this...
2. ### Electric Potential Energy of a System of Charges

Homework Statement A square of side a has a charge +Q at each corner. What is the electric potential energy of this system of charges? Express your answer in terms of the variables a, Q and appropriate constants. Homework Equations U=kq1q2/r The Attempt at a Solution I figured...
3. ### Energy Conservation - Electric Potential Energy

Homework Statement In proton-beam therapy, a high-energy beam of protons is fired at a tumor. The protons come to rest in the tumor, depositing their kinetic energy and breaking apart the tumor’s DNA, thus killing its cells. For one patient, it is desired that 0.10 J of proton energy be...
4. ### Setting up an Integral for the area of a surface of revolution

Homework Statement Set up, but do not evaluate, an integral for the area of the surface obtained by rotating the curve y=xe-x 1=<x=<3 about the y-axis. Homework Equations S=integral from a to b x 2pix ds where ds=sqrt(1+(dy/dx)2)dx The Attempt at a Solution The first thing I...
5. ### Walking away from two loudspeakers-destructive interference

Homework Statement You are standing 2.5 m directly in front of one of the two loudspeakers shown in the figure. They are 3.0 m apart and both are playing a 686 Hz tone in phase. As you begin to walk directly away from the speaker, at what distances from the speaker do you hear a minimum...
6. ### Finding the Time in a SHM Problem

Homework Statement Bungee Man is a superhero who does super deeds with the help of Super Bungee cords. The Super Bungee cords act like ideal springs no matter how much they are stretched. One day, Bungee Man stopped a school bus that had lost its brakes by hooking one end of a Super Bungee...
7. ### Ratio of Kinetic to Potential Energy of Simple Harmonic Oscillator

Homework Statement Calculate the ratio of the kinetic energy to the potential energy of a simple harmonic oscillator when its displacement is half its amplitude. Homework Equations KE=1/2mv2 = 1/2kA2sin2(wt) U=1/2kx2 = 1/2kA2cos2(wt) KEmax=1/2kA2 Umax=1/2KA2 The Attempt at a...
8. ### Kinematics - Projectile Motion

Homework Statement You and your friend have been hired to see if the catapult a movie company owns will be usable for a scene about a battle set in the middle ages. In the scene a catapult launches a 750 kg boulder that is supposed to hit the ground 350 m away. The director is worried the...