Answer:
a) What is the surface temperature, in °C, after 400 s?
T (0,400 sec) = 800°C
b) Yes, the surface temperature is greater than the ignition temperature of oak (400°C) after 400 s
c) What is the temperature, in °C, 1 mm from the surface after 400 s?
T (1 mm, 400 sec) = 798.35°C
Explanation:
oak initial Temperature = 25°C = 298 K
oak exposed to gas of temp = 800°C = 1073 K
h = 20 W/m².K
From the book, Oak properties are e=545kg/m³ k=0.19w/m.k Cp=2385J/kg.k
Assume: Volume = 1 m³, and from energy balance the heat transfer is an unsteady state.
From energy balance: 
Initial temperature wall = 
Surface temperature = T
Gas exposed temperature = 
Answer:
a) 280MPa
b) -100MPa
c) -0.35
d) 380 MPa
Explanation:
GIVEN DATA:
mean stress 
stress amplitude 
a) 
--------------1

-----------2
solving 1 and 2 equation we get

b) 
c)
stress ratio

d)magnitude of stress range

= 280 -(-100) = 380 MPa
Answer:
Dr. Engelbart, who would later help develop the computer mouse and other personal computing technologies, theorized that as electronic circuits were made smaller, their components would get faster, require less power and become cheaper to produce — all at an accelerating pace
Answer:
1425.78 N.m
Explanation:
Moments of force is calculated as ;
Moments= Force * distance
M= F*d
The S.I unit for moment of force is Newton-meter (N.m)
Given in the question;
Force = 72 lbs
1 pound = 4.45 N
72 lbs = 4.45 * 72=320.4 N
Distance= 15 ft
1ft= 0.3048 m
15 ft = 15*0.3048 = 4.57 m
d= 4.57 m
M= F*d
M=320.4*4.57 =1425.78 N.m