A student drops a rubber ball onto a surface. Assume that this is a closed system. The ball bounces, but each successive bounce
is shorter than the one before it. Eventually, the ball comes to a stop. Which statement provides evidence that supports the idea that energy is conserved in this closed system?
A. The ball moves through air, suggesting that the ball has mechanical energy.
B. The ball needs a push or pull to start moving, suggesting it needs a constant input of energy.
C. The ball makes a sound with each bounce, suggesting that some kinetic energy transformed into sound.
D. The ball bounces many times, suggesting the energy is used up efficiently
A. The ball moves through air, suggesting that the ball has mechanical energy.
B. The ball needs a push or pull to start moving, suggesting it needs a constant input of energy.
C. The ball makes a sound with each bounce, suggesting that some kinetic energy transformed into sound.
D. The ball bounces many times, suggesting the energy is used up efficiently
2 answers:
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Answer:
i) FALSE, ii) TRUE, iii) FALSE, iv) FALSE
Explanation:
When light (electromagnetic radiation) travels through a material medium, its speed is less than the speed of light in a vacuum. If we define the index of parts
n = c / v
where v is the speed of light in the material medium.
The direction of the ray can be determined by the law of refraction
n₁ sin θ₁ = n₂ sin θ₂
Let's apply these equations to our case where
nₓ <n_y
i) The expression of the refractive index
nₓ < n_y
v_y <vₓ
therefore the expression is FALSE
ii) If we use the law of refraction, the light, when passing from a medium with a lower start to another with a higher index, must approach the normal one, away from what would be the continuation of the path of the incident ray
so the expression is TRUE
iii) The speed of light is constant in all material media
the statement is FALSE
iv) light approaches normal
Let me clarify that the normal is a line perpendicular to the surface at the point of contact, not the direction of Io.
the statement of FALSE