Speed uses distance and velocity uses displacement in its calculation.
For 100 m race, distance = displacement. Hence speed = velocity
For 400m race, distance ≠ displacement. distance = 400m whereas displacement = 0m. Hence speed ≠ velocity
density of water = 
velocity of flow = 
radius of pipe = 
Height of second floor = 
Now we can use here Bernuoli's Equation to find the speed of water flow at second floor
Now in order to find the radius of pipe we can use equation of continuity
So radius of pipe at second floor is 0.034 meter
Average speed = total distance travelled ÷ total time taken
AS = (75km + 68km) ÷ (1hr + 2hr)
As = 143km ÷ 3hr
AS = 47.66667 km/hr
AS = 47.7 km/hr (3sf)
The time required for a moon to orbit around the earth is about 27-28 days
In order for lunar eclipse to occur the line that should be formed is:
Sun-Earth-Moon
because earth is making shade on moon
in order for solar eclipse to occur the line is now:
Sun-Moon-Earth
because moon is making a shade on earth (blocking sun = solar eclipse)
Therefore moon needs to make half of its orbit to go from behind the earth to in front of the earth.
28/2 = 14
Answer is 14
