6-3-rotational-motion_summary

The section "Rotational Motion" examines rotational kinematic variables and equations that are analogous to those in linear motion. By the end of the section, students will be able to describe these rotational variables and their equations, understand the concept of torque and lever arm, and solve problems related to torque and rotational kinematics. Examples of applications for rotational kinematics and torque are found in examples such as the fishing reel slowing down when the fish pulls the line or in a man pushing a spinning merry-go-round to change its motion. Students should review this section as part of preparing for physics lab exercises examining circular and rotational motion. Key takeaway points are summarized through the learning objectives, which include relating linear kinematics variables and their counterparts in rotational mechanics, as well as focusing on analyzing accelerated motion in two dimensions (including projectile and circular examples), and understanding forces and the effects of them on objects in physics standards. The main rotational variables described in this chapter are rotational velocity ω (the same angle swept by a radial path in time), rotational acceleration α, and the angular position or degree of rotation θ (measured from zero). Rotational velocity varies with angular position (curvilinear), rather than along a straight-line like linear velocity; angular acceleration can make rotational motion increase speed, slow down, or change direction; the SI unit of angular velocity (radians per second - rad/s) as well as units of α are described, using the time (seconds – s) and angular dimensions (radians). Lastly, equations to examine rotational motion in relationships to angular displacement or position θ, angle of rotation velocity ω, angular acceleration α, and time t as well as those equations' linear kinematics are provided for easier solution problem solving in this topic's realm.