Q: A 25.0 kg grindstone disc with a 0.250 m radius ( r ) rotates with an angular speed ( ω ) of 30.0 rad/s. When power to the disc is shut off, it decelerates and comes to rest over the course of 20.0 s. When the grindstone is shut off, a speck of dustContinue reading “AP PHYSICS: Rotational Kinematics”
Tag Archives: torque
AP PHYSICS: Pulleys, Torque, Tension, and the Moment of Inertia
Two spherical bearings of mass ( m1 ) and ( m2 ) are attached by belt to a pulley that is situated between them. An electric motor is also attached to the pulley, and it is positioned between these masses. When the motor is turned on, the pulley provides 15.0 N of tension on theContinue reading “AP PHYSICS: Pulleys, Torque, Tension, and the Moment of Inertia”
ENERGY AND MOMENTUM: Conservation of Energy, Linear Momentum, and Angular Momentum During a Collision
1. Momentum is always conserved when collisions occur. Momentum is defined as being a quantity of motion, and it is a product of mass and velocity. A small object travelling with a high velocity has great momentum ( Ex. A bullet ), and a massive object travelling with a low velocity has great momentum (Continue reading “ENERGY AND MOMENTUM: Conservation of Energy, Linear Momentum, and Angular Momentum During a Collision”
EQUILIBRIUM STATICS: Stationary and Moving Center of Mass Derivation
In physics, concepts like force, energy, and motion go hand-in-hand with one another. An unbalanced force will cause an object to accelerate. Equal and opposite force pairs will cause an object to remain at rest or maintain a constant velocity if it is already in motion. When an applied force causes an object or systemContinue reading “EQUILIBRIUM STATICS: Stationary and Moving Center of Mass Derivation”
ROTATIONAL MOTION: At What Rate will the Yo-Yo Accelerate?
Several forces must be taken into account to study the motion of a yo-yo. If we assume a hand to be stationary when a yo-yo begins its descent, a tension force acts upward upon the yo-yo’s string. Opposite to the tension force is the force exerted upon the system by the gravitational force of attractionContinue reading “ROTATIONAL MOTION: At What Rate will the Yo-Yo Accelerate?”
ROTATIONAL MOTION: What Distance Separates Two Projectiles Revolving Around a Common Center of Mass?
Q: Two projectiles separated by distance ( dt ) revolve around their center of mass ( cm = ½ dt ). Each projectile has a mass ( m ) of 4.81 x 1020 kg, and they have an instantaneous rotational speed ( ⍵ ) of 1.25 x 10-10 rad/s relative to the center of mass.Continue reading “ROTATIONAL MOTION: What Distance Separates Two Projectiles Revolving Around a Common Center of Mass?”
FORCE AND ACCELERATION: The Sum of all Torques Must Equal Zero
When a system is in static equilibrium, the sum of the forces acting upon the system must equal zero. In the diagram below, forces F1 and F2 exert torques upon the system: Recall that a torque ( 𝛕 = Fr sin θ ) has the ability to make a system rotate, and it is theContinue reading “FORCE AND ACCELERATION: The Sum of all Torques Must Equal Zero”
FORCE AND ACCELERATION: Systems of Torque and the Center of Mass
Thus far, physicists have not developed a concise definition of what constitutes mass and “ free space “. As a consequence, an overly simplistic definition of mass, albeit imperfect, may be used with convenience in laboratory settings. Mass, simply put, occupies free space. Relatively simple analyses of forces acting upon massive objects can be madeContinue reading “FORCE AND ACCELERATION: Systems of Torque and the Center of Mass”
ROTATIONAL MOTION: Rotational Inertia
Q: A student sits atop a freely rotating stool holding two dumbbells, each of which has a mass of 3.09 kg. When the student’s arms are extended horizontally outward, the dumbbells are 0.99 m from the axis of rotation. There are 180 degrees of separation between the extended arms. The student rotates with an angularContinue reading “ROTATIONAL MOTION: Rotational Inertia”
CENTRIPETAL ACCELERATION
Q: What is the centripetal acceleration of a point located 7.50 cm from the central axis of an ultracentrifuge spinning at a rate of 7.5 x 104 rev/min? A: The given rate of 7.5 x 104 revolutions per minute is converted to radians per second ( ⍵ ) in the latter stages of the solutionContinue reading “CENTRIPETAL ACCELERATION”
RENAISSANCE PHYSICS 