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Guilherme B.

Universidade Estadual Paulista


I am a Physicist. I completed my BSc degree in Physics at the University of Sao Paulo, in Brazil, and recently I defended my master's thesis in Theoretical Physics at the Sao Paulo State University. Next semester, I will start pursuing my PhD at Georgia Tech. My area of research is General Relativity.


MS Theoretical Physics
Universidade Estadual Paulista
BS Physics
Universidade de Sao Paulo

Topics Covered

Equilibrium and Elasticity
Motion Along a Straight Line
Motion in 2d or 3d
Newton's Laws of Motion
Electromagnetic Waves
Quantum Physics
Atomic Physics
Fluid Mechanics
Nuclear Physics
Physics Basics
Electric Charge and Electric Field
Kinetic Energy
Potential Energy
Energy Conservation
Rotation of Rigid Bodies
Dynamics of Rotational Motion
Moment, Impulse, and Collisions
Mechanical Waves
Wave Optics
Particle Physics
Periodic Motion
Applying Newton's Laws
Current, Resistance, and Electromotive Force
Direct-Current Circuits
Electromagnetic Induction
Alternating Current
Gauss's Law
Electric Potential
Capacitance and Dielectrics
Magnetic Field and Magnetic Forces
Temperature and Heat
Thermal Properties of Matter
The First Law of Thermodynamics
The Second Law of Thermodynamics
Sources of Magnetic field
Sound and Hearing
Reflection and Refraction of Light

Guilherme's Textbook Answer Videos

University Physics with Modern Physics

When an object is rolling without slipping, the rolling friction force is much less than the friction force when the object is sliding; a silver dollar will roll on its edge much farther than it will slide on its flat side (see Section 5.3). When an object is rolling without slipping on a horizontal surface, we can approximate the friction force to be zero, so that $a_x$ and $a_z$ are approximately zero and $v_x$ and $\omega_z$ are approximately constant. Rolling without slipping means $v_x = r\omega_z$ and $a_x = r\alpha_z$ . If an object is set in motion on a surface $without$ these equalities, sliding (kinetic) friction will act on the object as it slips until rolling without slipping is established. A solid cylinder with mass $M$ and radius $R$, rotating with angular speed $\omega_0$ about an axis through its center, is set on a horizontal surface for which the kinetic friction coefficient is $\mu_k$. (a) Draw a free-body diagram for the cylinder on the surface. Think carefully about the direction of the kinetic friction force on the cylinder. Calculate the accelerations $a_x$ of the center of mass and $a_z$ of rotation about the center of mass. (b) The cylinder is initially slipping completely, so initially $\omega_z = \omega_0$ but $v_x =$ 0. Rolling without slipping sets in when $v_x = r\omega_z$ . Calculate the $distance$ the cylinder rolls before slipping stops. (c) Calculate the work done by the friction force on the cylinder as it moves from where it was set down to where it begins to roll without slipping.

Chapter 10: Dynamics of Rotational Motion
Section 7: Gyroscopes and Precession
Guilherme B.
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