Answer:
ΔT = 59.9 ° C
Explanation:
For this exercise the brake energy is totally converted into heat
Let's calculate the vehicle energy
K = ½ m v²
Let's reduce the units to the SI system
v = 30 mph (1609.34 m / mile) (1h / 3600s) = 13.41 m / s
Em = K = ½ 1200 13.41²
K = 1.079 105 J
All this energy is transformed into heat
Em = Q
The expression for heat is
Q = m ΔT
ΔT = Q / m
The specific heat of iron is = 450 J / Kg ºC
ΔT = 1,079 105 / (4.0 450)
ΔT = 59.9 ° C
In the image below, the focus lines are shown. The step can be done to bring the apple into focus is make the lens rounder. The correct option is A.
<h3>What is lens?</h3>
The lens is in spherical shape may be diverging or converging.
As light enters the eye, it is focused on the retina. Changing the pupil diameter, regulates the amount of light entering the eye. Changing lens shape will focus the light.
The changes in lens shape needed to maintain focus as the object distance changes.
Thus, the correct option is A.
Learn more about lens.
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