Wow I have no idea kid............
Answer:
36.87 km/h
Explanation:
Convert all the units in SI system
1 mile = 1609.34 m
d1 = 6 mi = 9656.04 m
t1 = 15 min = 15 x 60 = 900 s
d2 = 3 mi = 4828.02 m
t2 = 10 min = 10 x 60 = 600 s
d3 = 1 mi = 1609.34 m
t3 = 2 min = 2 x 60 = 120 s
d4 = 0.5 mi = 804.67 m
t4 = 0.5 min = 0.5 x 60 = 30 s
Total distance, d = d1 + d2 + d3 + d4
d = 9656.04 + 4828.02 + 1609.34 + 804.67 = 16898.07 m = 16.898 km
total time, t = t1 + t2 + t3 + t4
t = 900 + 600 + 120 + 30 = 1650 s = 0.4583 h
The ratio of the total distance covered to the total time taken is called average speed.
Average speed = 16.898 / 0.4583 = 36.87 km/h
Air spaces are used in insulation because air is a poor conductor.
Answer: c) 90 m/s
Explanation:
Given
Invest velocity, v1 = 250 m/s
Inlet specific enthalpy, h1 = 270.11 kJ/kg = 270110 J/kg
Outlet specific enthalpy, h2 = 297.31 kJ/kg = 297310 J/kg
Outlet velocity, v2 = ?
0 = Q(cv) - W(cv) + m[(h1 - h2) + 1/2(v1² - v2²) + g(z1 - z2)]
0 = Q(cv) + m[(h1 - h2) + 1/2(v1² - v2²)]
0 = [(h1 - h2) + 1/2(v1² - v2²)]
Substituting the values of the above, we get
0 = [(270110 - 297310) + 1/2 ( 250² - v²)
0 = [-27200 + 1/2 (62500 - v²)]
27200 = 1/2 (62500 - v²)
54400 = 62500 - v²
v² = 62500 - 54400
v² = 8100
v = √8100
v = 90 m/s
