Suppose a wheel with a tire mounted on it is rotating at the constant rate of 3.33 times a second. A tack is stuck in the tire a
2 answers:
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Answer:
v = 28.7 m/s
Explanation:
- According to the Work Energy Theorem, the work done by external forces on the system, is equal to the change in the kinetic energy of the system.
- In absence of friction, the only force that does work , producing a displacement in the direction of the force, is the component of gravity parallel to the slide:
- The displacement d,along the slide, can be found from the definition of the sine of an angle, as follows:
- Solving for d, we get:
- Now, the work done by Fgp, is just the product of the force times the displacement, as follows:
- From (1) and (2) we can find W as follows:
- This expression must be equal to ΔK, as follows:
- Simplifying common terms, we can solve for v (the velocity of the sled at the bottom of the slide), as follows:
- The velocity of the sled at the bottom of the slide is 28.7 m/s, taking as positive the direction down the slide.
<h2>Answer: Albedo
</h2>
The <u>albedo</u> is an amount that expresses the percentage of radiation a surface reflects with respect to the incident radiation.
In other words:
This amount allows us to know the level of radiation that <u>reflects</u> a surface compared to the total <u>radiation it receives</u>.
According to this, light surfaces such as snow covered ground or white sand will have a higher albedo than dark surfaces such as carbon covered ground. It is also important to note, the albedo will be higher on glossy surfaces than on matte surfaces.
It should be noted that the albedo of the Earth is on average about , which means that part of the radiation received by the Sun is absorbed and another part reflected back to space.