1. Why is the linear speed greater for a horse on the outside of a merry-go-round than for a horse closer to the center? Greater radius has a greater circle in the same time, therefore greater speed
2. What is meant by tangential speed? Another way to say linear speed, dist/time
3. Distinguish between tangential speed and rotational speed.
Tangential is measured in meters per second. Rotational is simply rotations per second. All points of rotating object have same rotational speed but different linear speed.
4. How are tangential speed and rotational speed related? If the rotational speed of a platform is doubled, how does tangential speed anywhere on the platform change?
They are both speeds but measured differently. Tangential speed depends on how far from center you are.
Rotational doesn’t.
5. What is the relationship between tangential speed and distance from the center of the rotational axis? Give an example. See answer above
6. What is rotational inertia, and how does it compare to inertia as studied in previous chapters?
Resistance to rotate.
7. Inertia depends on mass; rotational inertia depends on mass and something else. What?
Depends on WHERE mass is located in regards to the center of rotation
8. Does the rotational inertia of an object differ for different axes of rotation?
Yes. Depends on what axis object is rotating about that determines this. recall pencil from handout.
9. Consider three axes of rotation for a pencil: along the lead; at right angles to the lead at the middle; at right angles to the lead at one end. Rate these for rotational inertia.
Increases as it was listed in question as mass gets further from pivot.
10. Which is easier to get swinging, a baseball bat held at the end, or one held closer the massive end (choked up)?
Choked up…moves pivot closer to mass, reduces rotational inertia
11. Why does bending your legs when running enable you to swing your legs to and fro more rapidly?
Brings mass closer to pivot, decreases rotational inertia
12. When you whirl a can at the end of a string in a circular path, what is the direction of the force that is exerted on the can? Inward, towards the center.
13. Is it an inward force or an outward force that is exerted on the clothes during the spin cycle of an automatic washer? inward
14. If the string breaks that holds a whirling can in its circular path, what kind of force causes it to move in a straight-line path—centripetal, centrifugal, or no force? What law of physics supports your answer?
NO force.
15. If you are not wearing a seat belt and you slide across your seat and slam against a car door when the car rounds a curve, what kind of force is responsible—centripetal, centrifugal, or no force? Support your answer.
NO force…just inertia wanting to go straight
16. Why is centrifugal force in a rotating frame called a “fictitious force”?
Because it’s your inertia that makes you feel that way…no force present