Answer:Rolling friction is friction that acts on objects when they are rolling over a surface. Rolling friction is much weaker than sliding friction or static friction. This explains why most forms of ground transportation use wheels, including bicycles, cars, 4-wheelers, roller skates, scooters, and skateboards.
Explanation:
Answer:
a. La ciencia.
Explicación:
El método científico de la física experimental y su búsqueda de respuestas tiene un principio básico que es la ciencia. La ciencia es la aplicación del conocimiento del mundo natural y social siguiendo una metodología sistemática basada en evidencias. Sin evidencias no hay aceptación de la observación ni se debe hacer teoría porque la evidencia es el principal criterio para aceptar o rechazar una hipótesis.
The answer is 1.01 x 10^(-11) N. I arrived to this answer through calculating the GPEs of both balls. Bjorn's ball has a GPE of 1.402 x 10^(-11) N. Billie Jean's ball has a GPE of <span>2.503 x 10^(-11) N. I subtracted the two and I found that Billie Jean's tennis ball has a GPE of 1.01 x 10^(-11) more than Bjorn's tennis ball.</span>
Answer: 
Explanation:
According to Newton's law of universal gravitation:
Where:
is the module of the force exerted between both bodies
is the universal gravitation constant.
and 
are the masses of both bodies.
is the distance between both bodies
In this case we have two situations:
1) Two bags with masses 
and mutually exerting a gravitational attraction 
on each other:
(1)
(2)
(3)
2) Two bags with masses 
and 
mutually exerting a gravitational attraction 
on each other (assuming the distance between both bags is the same as situation 1):
(4)
(5)
(6)
Now, if we isolate 
from (3):
(7)
Substituting found in (7) in (6):
(8)
(9)
Simplifying, we finally get the expression for in terms of
:
A transformer is used to increase or decrease a voltage. BUT ... it has to be an AC voltage, or the transformer doesn't work.
