Air Pressure is a force that is exerted onto your body by air molecules.
        
             
        
        
        
Answer:
Here are some examples of tropism in plants : Sunflowers are one of the best examples of positive phototropism , as they always grow facing the sun. 
Explanation:
 Although some experts consider that perhaps such a clear growth movement should not be considered tropism.
 
        
             
        
        
        
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)
 
        
             
        
        
        
Answer: A river delta is a landform created by deposition of sediment that is carried by a river as the flow leaves its mouth and enters slower-moving or stagnant water. This occurs when a river enters an ocean, sea, estuary, lake, reservoir, or (more rarely) another river that cannot carry away the supplied sediment. The size and shape of a delta is controlled by the balance between watershed processes that supply sediment.