A bottle opener is an example of a simple machine. When you pull up on the opene
ID: 1588425 • Letter: A
Question
A bottle opener is an example of a simple machine. When you pull up on the opener, the opener pulls up on the bottle cap. Use the illustrations to answer the question below. In terms of what you have learned about machines, explain how the bottle cap opener works. Explain why the bottle cap opener does not violate the law of conservation of energy. A person jumps from his front step to the ground. If the person bends his knees, the jump doesn't hurt at all - if he doesn't bend his knees, however, he finds the jump very painful! (Don't try this yourself!) Given what you have learned about momentum, explain why this in the case.Explanation / Answer
34 part A
The bottle cap is open because the bottle opener is a machine simple, lever where the fulcrum point corresponds to the tip which is located in the center of the lid, resistance (R) is the short tip which is at the end of the cover and the power (P) is the strength of the hand at the end of the uncovered. This configuration is called second type lever and this have the relation
P Bp = R Br
Bp symbol for the distance from the support to the application of force (long corkscrew + D/2)
Br symbol of the distance from support to resistance (top radio = D/2)
En general Bp > Br
This looks at the force that must be applied to decreases with the length of the lever Bp
Part B
The power given by the applied force is converted into kinetic energy in the upward motion and subsequently becomes elastic potential energy with the bending of the cover, all the energy is stored in the change of position of the molecules that form the lid. As a result all the initial energy is transformed into elastic energy and therefore there is no violation of the law of conservation
35.
When a person jumps from a step acquires a speed, so it increases the amount of movement is zero at a speed v. This amount of movement becomes transform impulse when it collides with the floor, this energy must be absorbed by the system that may break if it is rigid or bending, pain in the feet and knees.
On the other hand in system can be bent, with the movement of the knee the amount of movement that it must absorb in the same, the body has the same initial speeds and ultimately before the clash but after the shock it must absorb in two part the rotational movement of the knees and the soles of the feet, thus the effect on the system is less.
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