Elizabeth, Colby, Ashley, Brittany

State and Explain Concepts  Torque is the tendency of a force to cause rotation about an axis.  Lever arm is he distance from the turning axis to the point of contact.  Rotational Inertia is the resistance of an object to changes in its rotational state of motion.  Linear Momentum is the product of the mass and the velocity of an object.  Angular Momentum is the "inertia of rotation" of a rotating object.  Rotational Velocity is when a direction is assigned to rotational speed.  The Law of Conservation of Angular Momentum states that if no unbalanced external torque acts on a rotating system, the angular momentum of that system is constant.

Historical Perspective  According to Galileo you have to have Newton's Second Law of Motion in order to calculate rotational motion. One way we can measure rotatiional motion is by " you and I face each other, standing on a slippery floor. We both hold our hands up at shoulder level, say. Then you hold my right hand with your left hand, and my left hand with your right hand. Then at the same time you begin to push on my right hand and pull on my left hand with the same force. What happens? If the floor is slippery enough, we'll both begin to rotate." This is a way to affectively show how rotational motion works. So we will, in general, begin to rotate, unless frictional forces come into play to balance the applied forces. We measure this my F=ma Newton's second law of motion. "Rotational Motion." Rotational Motion. Web. 2 Dec

Application of Concepts  Rotational Motion is used everyday in many different ways. Turning a door knob, turning on the faucet, or tightening a bolt. This turning force produces a torque. When a gymnast pivots around the horizonatl bars with her body fully extended, she has the greatest amount of rotational inertia is the greatest.

Think and Explain Questions  1) A screwdriver with a long handle is better for prying open a stuck cover from a can of paint while a screwdriver with a thick handle is better for turning stubborn screws.  2) The mass of the rock shown in figure A is Two Kg.  3) The mass of the meter stick is 1 Kg.  4) Longer feet would help you to do this because the issue occurs when your center of gravity reaches out in front of your toes.  5) It helps because holding your arms out increases your rotational inertia, giving you further leverage.  6) The bowling ball because it has a greater mass.  7) it prevents the front edge of the Frisbee from stalling as well as provides greater stability when the disk is spinning by supplying a greater amount of angular momentum.  8) you do so by grasping it towards the tail end of the ball, lining up your outer fingers with the laces. As for why it's because you want the inertia to help guide the ball towards the target.  9) It would result in two thirds of a rotation per second.  10) It slows, this is supported by the Law of conservation of angular momentum.

Review Questions  1. The effects of force and torque on an object are that force is used to make an object move and torque is used to turn or rotate an object.  2. The lever arm of a force is the distance from the turning axis to the point of contact if the force is perpendicular.  3. The force should be applied perpendicular to produce the maximum torque.  4. Clockwise and counterclockwise torques must equal out to achieve balance.  5. You cannot stand heels and back to a wall and bend over to touch your toes and stand back up because your feet are not beneath your center of gravity which causes a torque.  6. A football must be kicked in line with the center of gravity so that it does not travel end-over-end.  7.The law of inertia for rotation is that an object rotating about an axis tends to keep on rotating about that axis.  8. The two quantities that make up rotational inertia are mass and torque.  9. A short pendulum swings more frequently than a long pendulum because the long pendulum has a greater rotational inertia.  10. Your legs swing to and fro more rapidly when they are bent because they have less rotational inertia then when they are outstretched.  11. The large ball will have a greater acceleration rolling down an incline than the smaller ball.  12. The solid disc will have a greater acceleration rolling down an incline than a hoop.  13. A person can vary their own rotational inertia by using different axes of rotation or by extending different parts of their body.  14. Rotational velocity is when a direction is added to a rotational speed.  15. Linear momentum is the inertia of motion and angular momentum is inertia of rotation.  16. The motion the torque produces is that the wheel will slowly process about a vertical axis.  17. The law of inertia for angular momentum is that an object or system of objects will maintain its angular momentum unless acted upon by an unbalanced external torque.  18. Saying that angular momentum is conserved means that there is no external torque.  19. The skater's rate of spinning will increase by twice of what the rate originally was.  20. The gymnast's angular momentum would be conserved and his rotational speed would change based on how he configured his body.