# Physics Essay

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Physics Note Test Circular acceleration French Cyclist , Cathy Marsal cycled 41.112 km/hour. Calculate the centripetal acceleration (in m/s2) with respect to the center of the earth. (circumference 38,870km) since C=2πr r=C2π 38,8700002π=6186000 Ac=V2tr 41.112km/h3.6m/s26186000 =2.11x10-5 m/s2 Centripetal Force * Force that keeps an object going in a circular path * Also directed toward the center of rotation E.g. Ball on a String * inertia maintains ball’s motion in a linear path * tension on the string is an applied net external force directed toward the center of rotation * Causes a constant change in velocity , making the ball follow a circular path * Magnitude of centripetal force is found using Newton’s 2nd law F=ma Fc=mac Since ac=V2tr Fc=m V2tr * No different from any other force- can be Fk * Friction is the force that makes a car go in a circle * Frictional Force between a cars tires and the pavement * Gravitational force is the centripetal force that keep the moon in orbit around the earth Centripetal vs. Centrifugal Centripetal =/=‘ Centrifugal’ * Riding in your car, as you go around a turn you feel a “force” pushing you in the direction opposite to the turn * The “force” is commonly referred to as “centrifugal” force * This is wrong * Centrifugal force is a special force that is the reaction form to centripetal force Inertia * The “force” you feel when you travel in circular motion is inertia * Your body’s inertia tends to keep you in motion in the direction you are going * Changing that direction produced a sensation as a pull or push is actually due to the fact that your body resists the change * Inertial frame of reference Centripetal Force * The force that maintains circular motion on the passenger is the force of static friction between the