Question

A packet is thrown up with some initial speed, the pack reaching a certain maximum height. The air is dense and does have some friction. Consider the following amounts: a) The change of kinetic energy during the process b) The work performed by the gravity during the process c) The change of potential energy during the process d) The work performed by the friction Determine the signs of the previous quantities respectively.

a) negative, negative, positive, negative
b) negative, negative, positive, positive
c) positive, negative, positive, negative
d) positive all
e) none of the above
f) all negative

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Un paquete es lanzado hacia arriba con cierta velocidad inicial, llegando el paquete hasta cierta altura máxima. El aire es denso y sí presenta algo de fricción. Considere las siguientes cantidades:

a) El cambio de energía cinética durante el proceso

b) El trabajo que realiza la gravedad durante el proceso

c) El cambio de energía potencial durante el proceso

d) El trabajo que realiza la fricción

Determine los signos de las cantidades anteriores respectivamente

a) negativo, negativo, positivo, negativo
b) negativo, negativo, positivo, positivo
c) positivo, negativo, positivo, negativo
d) positivos todos
e) ninguna de las anteriores
f) negativos todos

Answer 1

A packet is thrown up with some initial speed, the pack reaching a certain maximum height. The air is dense and does have some friction. Consider the following amounts: a) The change of kinetic energy during the process b) The work performed by the gravity during the process c) The change of potential energy during the process d) The work performed by the friction Determine the signs of the previous quantities respectively.

a) negative, negative, positive, negative

a)this is the right answer as when ball goes up v decreases and hence k.e becomes negative

b)the work performed by the gravity is also negative because gravity is working against the  motion of ball

c)as height increases so does the P.E=mgh increases hence P.E is positive

d)in the end friction also work negatively on the motion