Question

from the physics classrooms physics interactive

1. how does the speed at point e compare to the speed at point g? explain why this is true.
2. rank the pe for the eight locations, from the lowest pe to the highest pe. write letters in the blanks and place < or = symbols between the letters.
3. rank the ke for the eight locations, from the lowest ke to the highest ke. write letters in the blanks and place < or = symbols between the letters.
4. mac and tosh are arguing about the track design. mac claims that the car is moving fastest at point f because it is furthest along the track. tosh disagrees, claiming that the car moves fastest at point f because point f is at the lowest height. who do you agree with? make a modification of the track design for point f and gather some evidence to support one claim or the other. then discuss what changes you made, what observations were made, and the reasoning that supports one of the claim of either mac or tosh.
5. does changing the height of point c affect the speed of the coaster car at point d? try it and find out. once certain of the answer, make a claim and support it with evidence (data) and reasoning.

Explanation:

4.

Step1: Consider la conservación de la energía mecánica

La energía mecánica total $E = PE+KE$ es constante (suponiendo sin rozamiento). La energía potencial gravitacional $PE = mgh$ y la energía cinética $KE=\frac{1}{2}mv^{2}$. Si el punto E está más alto que el punto G, entonces $PE_E>PE_G$. Como $E$ es constante, entonces $KE_E < KE_G$. Y como $KE=\frac{1}{2}mv^{2}$, la rapidez $v=\sqrt{\frac{2KE}{m}}$, por lo que la rapidez en el punto E es menor que en el punto G.

Step1: Usar la fórmula de energía potencial gravitacional

La energía potencial gravitacional $PE = mgh$, donde $m$ es la masa, $g$ es la aceleración gravitacional y $h$ es la altura. Ordenamos los puntos de menor a mayor altura para ordenar la energía potencial.

Step1: Usar la relación entre PE y KE

Como $E = PE + KE$ es constante, los puntos con menor PE tendrán mayor KE. Ordenamos los puntos en orden creciente de PE para obtener los puntos en orden creciente de KE.

Answer:

La rapidez en el punto E es menor que la rapidez en el punto G.

5.