Answer:
3 km/h
Explanation:
Let's call the rowing speed in still water x, in km/h.
Rowing speed in upstream is: x - 2 km/h
Rowing speed in downstream is: x + 2 km/h
It took a crew 9 h 36 min ( = 9 3/5 = 48/5) to row 8 km upstream and back again. Therefore:
8/(x - 2) + 8/(x + 2) = 48/5      (notice that: time = distance/speed)
Multiplying by x² - 2², which is equivalent to (x-2)*(x+2)
8*(x+2) + 8*(x-2) =  (48/5)*(x² - 4)
Dividing  by 8
(x+2) + (x-2) = (6/5)*(x² - 4)
2*x = (6/5)*x² - 24/5
0 =  (6/5)*x² - 2*x - 24/5
Using quadratic formula






A negative result has no sense, therefore the rowing speed in still water was 3 km/h
 
        
             
        
        
        
Answer
given,
Echo time = t = 1000 s
speed = ?

a) speed of electromagnetic wave

wave travels Venus two time



 d = 1.5 x 10¹¹ m
b) now, echo time
     
     
     
           t = 5 x 10⁻⁷ s
 
        
             
        
        
        
Answer:
is always negative
Explanation:
Air resistance is a non-conservative force it opposes the motion of an object.It is a force that is always directed opposite to the displacement.
 
        
                    
             
        
        
        
The longer the time between the arrival of the P-wave and S-wave, the <u>farther away</u> is the epicenter.
<h3>
What is epicenter and the relation between P-wave and S-wave?</h3>
- The point on the earth's surface vertically above the hypocenter (or focus), point in the crust where a seismic rupture begins is said to be epicenter.
- There are two types of waves during earthquakes, they are:
- P - wave
- S - wave
-  Each seismograph records the times when the first (P waves) and second (S waves) seismic waves arrive. 
- From the graph, through the information, scientists can determine how fast the waves are traveling.
- The longer the time between the arrival of the P-wave and S-wave, the farther away is the epicenter.
Hence, Option B is the correct answer.
Learn more about epicenter,
brainly.com/question/28136716
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