(a) Neil A. Armstrong was the first person to walk on the moon. The distance between the earth and the moon is . Find the time i
1 answer:
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.
You might be interested in
Answer:
The first part can be solved via conservation of energy.
For the second part,
the free body diagram of the car should be as follows:
- weight in the downwards direction
- normal force of the track to the car in the downwards direction
The total force should be equal to the centripetal force by Newton's Second Law.
where because we are looking for the case where the car loses contact.
Now we know the minimum velocity that the car should have. Using the energy conservation found in the first part, we can calculate the minimum height.
Explanation:
The point that might confuse you in this question is the direction of the normal force at the top of the loop.
We usually use the normal force opposite to the weight. However, normal force is the force that the road exerts on us. Imagine that the car goes through the loop very very fast. Its tires will feel a great amount of normal force, if its velocity is quite high. By the same logic, if its velocity is too low, it might not feel a normal force at all, which means losing contact with the track.