I went back through my book again to find the answers can you check them?
10. when rewinding a an audio tape or vdieotape, one reel winds fastest at the end. which reel is this? why does it speed up? (this one I understand. I think that it has something to do with rotational intertia or tangential speed, not too sure)
15.the wheels of railroad trains are tapered, a feature especailly important on curves. how if at all does the amount of taper relate to the curving of the tracks? (this question I don't understand)
20. flamingos are frequently seen standing on one leg with the other lifted. what can you say about the birds center of mass with respect to the foot on which it stands?
-because their center of gravity lies above its base of the support, therefore it is more stable
23. the front wheels located far out in front of the racing vehicle help to keep the vehicle from nosing upward when it accelerates. What physics concepts play a role here?
-centrifugal force
I can certainly help you check your answers and provide explanations for each question.
10. When rewinding an audio tape or videotape, one reel winds fastest at the end. Which reel is this? Why does it speed up?
To find the answer to this question, you can consider the concept of rotational inertia. When a tape is rewound, the reel that initially has less tape on it will wind faster at the end. This is because the more tape there is on a reel, the greater the rotational inertia of the reel, which resists rapid acceleration. As the tape gets transferred from one reel to another during rewinding, the reel that had less tape will gradually gain more, reducing the difference in tape amount between the reels. Consequently, the reel that had less tape will speed up to catch up with the other reel.
15. The wheels of railroad trains are tapered, a feature especially important on curves. How, if at all, does the amount of taper relate to the curving of the tracks?
The tapering of railroad train wheels is essential for effective navigation on curved tracks. The amount of taper, also known as the conicity or wheel taper, determines the difference in diameter between the inside and outside edges of the wheel. A greater amount of taper means a larger difference in diameter.
When a train goes around a curve, the outside wheel has to cover a longer distance compared to the inside wheel. The taper compensates for this difference by ensuring that the outside wheel has a slightly larger diameter than the inside wheel. This enables the wheels to maintain contact with the rails and prevent derailing during turns. The taper essentially helps the train negotiate the curve by allowing the wheels to roll smoothly while accounting for the variation in distance between the inner and outer rails.
20. Flamingos are frequently seen standing on one leg with the other lifted. What can you say about the bird's center of mass with respect to the foot on which it stands?
Your answer is correct. When a flamingo stands on one leg, its center of mass remains positioned above the base of support, which is the foot it stands on. This alignment between the center of mass and the base of support enhances stability. By having its center of gravity above its foot, the bird ensures that any perturbations or slight movements won't easily tip it over. This stable posture allows flamingos to conserve energy while resting or sleeping on one leg.
23. The front wheels located far out in front of a racing vehicle help to keep the vehicle from nosing upward when it accelerates. What physics concepts play a role here?
The concept of centrifugal force doesn't directly apply here. Instead, you can consider Newton's laws of motion to understand the physics behind this situation.
When a racing vehicle accelerates, it experiences a force in the forward direction. According to Newton's third law, the vehicle exerts an equal and opposite force on the ground. This ground reaction force acts as a counterforce to the vehicle's acceleration.
The position of the front wheels far out ahead of the vehicle contributes to balancing these forces. The forward position creates a longer lever arm, increasing the moment of inertia of the vehicle about its center of mass. This larger moment of inertia helps resist the nosing upward effect that occurs due to the acceleration force. Consequently, the front wheels play a role in keeping the vehicle level during acceleration, enhancing stability and control.
I hope these explanations help clarify your answers. Let me know if you have any further questions!