Answer:
The first situation is impossible.
Explanation:
"An object has constant non-zero velocity and changing acceleration."
Not possible, acceleration is the change of velocity. For velocity to remain constant the acceleration must remain zero. If acceleration is changing it might be zero at some point, but will not remain zero, so the velocity will change.
"An object has zero velocity but non-zero acceleration."
An object might have a velocity of zero at some point while under an acceleration. An example of this is an object that is thrown upwards. At the top of the trajectory it will have a velocity of zero but will be under the acceleration of gravity.
"An object has constant non-zero acceleration and changing velocity."
This is what any object in free fall do.
"An object has velocity directed east and acceleration directed east."
No problem with that.
"An object has velocity directed east and acceleration directed west."
No problem with that, it will reduce its velocity.
Answer:
1) f= 8.6 GHz
2) t= 0.2 ms
Explanation:
1)
- Since microwaves are electromagnetic waves, they move at the same speed as the light in vacuum, i.e. 3*10⁸ m/s.
- There exists a fixed relationship between the frequency (f) , the wavelength (λ) and the propagation speed in any wave, as follows:
- Replacing by the givens, and solving for f, we get:
⇒ f = 8.6 Ghz (with two significative figures)
2)
- Assuming that the microwaves travel at a constant speed in a straight line (behaving like rays) , we can apply the definition of average velocity, as follows:
where v= c= speed of light in vacuum = 3*10⁸ m/s
d= distance between mountaintops = 52 km = 52*10³ m
⇒ t = 0.2 ms (with two significative figures)
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