# Circular Motion - Midland Independent School District Circular Motion = the movement of an object at constant speed around a circle with fixed radius Axis straight line around which rotation takes place Rotation object turns around an internal axis Ex. Ice skater Revolution object turns around an external axis

Ex. Earth around the sun Rotational Speed Linear speed distance/time Tangential speed speed along a circular path

Rotational speed number of rotations per unit of time Example: Carousel horses travel at same rotational speed but different tangential speed Linking tangential and rotational speed Tangential speed is radial distance times the rotational speed V = r

Centripetal Force Force that causes an object to follow a circular path Ex. Force holding occupants safely in a rotating carnival ride Fnet = mv2 r Centripetal Acceleration

Always points toward the center of the circular motion. Period (T) = time needed for an object to make one complete revolution Distance traveled = circumference Circumference = 2r = dr = r = dd Other formulas

Centripetal Acceleration equals the velocity squared divided by the radius Ac = v2/r The number of revolutions equals the distance traveled divided by the circumference Revolutions = distance/circumference Sample problems

If a wheel has a diameter of 0.51 m and the wheel travels for 15 m, how many revolutions will it make? What is the tension in a 3.2 m length of string that whirls a 1.5 kg mass at 2.1 m/s in a horizontal circle?