Answer:
surface temperature of the chip located 120 mm Ts=42.5°C
surface temperature of the chip in Mexico Ts=46.9°C
Explanation:
from the energy balance equation we have to:
q=E=30W
from Newton´s law:
Ts=Tα+(q/(h*A)), where A=l^2
N=h/k=0.04*(Vl/V)^0.85*Pr^1/3
data given:
l=0.12 m
v=10 m/s
k=0.0269 W/(m*K)
Pr=0.703
Replacing:
h=0.04*(0.0269/0.12)*(10*0.12)/((16*69x10^-6))^0.85*(0.703^1/3) = 107 W/m^2*K
The surface temperature at sea level is equal to:
Ts=25+(30x10^-3/107*0.004^2)=42.5°C
h=0.04*(0.0269/0.12)*((10*0.12)/(21*81x10^-6))^0.85*(0.705^1/3)=85.32 W/(m*K)
the surface temperature at Mexico City is equal to:
Ts=25+(30x10^-3/85.32*0.004^2)=46.9°C
Answer:
Amplitude and wavelength
Explanation:
- The amplitude of a wave is the maximum displacement of the wave, measured with respect to the equilibrium position (so, for a water wave it is the maximum height of the wave relative to the equilibrium position)
- The wavelength of a wave is the distance between two consecutive crests (or throughs) of a wave. So, for a water wave, it is the distance between two consecutive waves
Therefore, in the example in the problem we have:
- 2 meters corresponds to the amplitude
- 35 meters corresponds to the wavelength
Answer:
D
Explanation:
We must never use a piece of pipe as a leverage extension on the handle on a wrench.
Hence option d is correct.
Answer:
R (120) = 940Ω
Explanation:
The variation in resistance with temperature is linear in metals
ΔR (T) = R₀ α ΔT
where α is the coefficient of variation of resistance with temperature, in this case α = -0,0005 / ºC
let's calculate
ΔR = 1000 (-0,0005) (120-0)
ΔR = -60
Ω
ΔR = R (120) + R (0) = -60
R (120) = -60 + R (0)
R (120) = -60 + 1000
R (120) = 940Ω
