Which best explains why a wood- burning fireplace represents an open system?
a.)because they are all made of brick
b.)because the ashes have to be swept away
c.)because they can be used for cooking
d.)because a fire requires oxygen from the atmosphere to burn

Determine the amount of work done when a crane lifts a 100-n block form 2m above the ground to 6m above the ground

Light traveling in a medium with a refractive index 1.19 is incident on a plate of another medium with index of refraction 1.79. at what angle of incidence is the reflected light fully polarized?

According to newton’s law of universal gravitation, which statements are true? as we move to higher altitudes, the force of gravity on us decreases. as we move to higher altitudes, the force of gravity on us increases. as we gain mass, the force of gravity on us decreases. as we gain mass, the force of gravity on us increases. as we move faster, the force of gravity on us increases.