You are a surgeon operating on a broken bone. You find a large area, swollen with blood, that surrounds the break site. What is
2 answers:
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Answer:
μsmín = 0.1
Explanation:
- There are three external forces acting on the riders, two in the vertical direction that oppose each other, the force due to gravity (which we call weight) and the friction force.
- This friction force has a maximum value, that can be written as follows:
where μs is the coefficient of static friction, and Fn is the normal force,
perpendicular to the wall and aiming to the center of rotation.
- This force is the only force acting in the horizontal direction, but, at the same time, is the force that keeps the riders rotating, which is the centripetal force.
- This force has the following general expression:
where ω is the angular velocity of the riders, and r the distance to the
center of rotation (the radius of the circle), and m the mass of the
riders.
Since Fc is actually Fn, we can replace the right side of (2) in (1), as
follows:
- When the riders are on the verge of sliding down, this force must be equal to the weight Fg, so we can write the following equation:
- (The coefficient of static friction is the minimum possible, due to any value less than it would cause the riders to slide down)
- Cancelling the masses on both sides of (4), we get:
- Prior to solve (5) we need to convert ω from rev/min to rad/sec, as follows:
- Replacing by the givens in (5), we can solve for μsmín, as follows:
Answer:
a)<em> It took 1.28 seconds to Neil Armstrong's voice to reach the Earth via radio waves. </em>
b) <em>The minimum time that will be required for a message from Mars to reach the Earth via radio waves is 192 seconds. </em>
Explanation:
The electromagnetic spectrum is the distribution of radiation due to the different frequencies at which it radiates and its different intensitie. That radiation is formed by electromagnetic waves, which are transverse waves formed by an electric field and a magnetic field perpendicular to it.
The distribution of the radiation in the electromagnetic spectrum can also be given in wavelengths, but it is more frequent to work with it at frequencies:
- Gamma rays
- X-rays
- Ultraviolet rays
- Visible region
- Infrared
- Microwave
- Radio waves.
Any radiation that belongs to electromagnetic spectrum has a speed in vacuum of .
<em>a) Find the time it took for his voice to reach the Earth via radio waves.</em>
To know the time that took for Neil Armstrong's voice to reach the Earth via radio waves, the following equation can be used:
(1)
Where v is the speed of light, d is the distance and t is the time.
Notice that t can be isolated from equation 1.
(2)
The distance from the Earth to the Moon is , therefore.
Hence, it took 1.28 seconds to Neil Armstrong's voice to reach the Earth via radio waves.
<em>b) Determine the minimum time that will be required for a message from Mars to reach the Earth via radio waves.</em>
The distance from the Earth to the Mars at its closest approach is , therefore.
Hence, the minimum time that will be required for a message from Mars to reach the Earth via radio waves is 192 seconds.
Answer:
The distance is 55.636 billion miles, or 528.2 AU.
Explanation:
Since the distance from the Sun to Neptune is 2.7818 billion miles, the distance from the Sun to Planet Nine would be 20 times that, which is:
or 55.636 billion miles.
Since 1 astronomical unit (AU) is 93 million miles, that distance is also: