Answer:
(a) 2.542 cm
(b) 272.7°C
Explanation:
diameter, d = 2.540 cm
T1 = 20°C
α = 11 x 10^-6 /°C
(a) Let d' be the diameter.
T2 = 87°C
Use he formula for the areal expansion
A' = A ( 1 + βΔT)
where, β is the coefficient of areal expansion and ΔT is teh rise in temperature, A' be the area at high temperature and A be the area at low temperature.
β = 2 α = 2 x 11 x 106-6 = 22 x 10^-6 /°C
So,
D'^2 = 2.54^2 ( 1 + 22 x 10^-6 x 67)
D' = 2.542 cm
(b) Let the change in temperature is ΔT.
Use the formula for the volumetric expansion
ΔV = V x γ x ΔT
Where, γ = 3 x α = 3 x 11 x 10^-6 = 33 x 10^-6 /°C
0.9/100 = 33 x 10^-6 x ΔT
ΔT = 272.7°C
Answer:
a)6.67 m/s2
b)16.7 rad/s2
c)increasing angular acceleration
Explanation:
a) It's because the system is not just mass of the man, it consists of the man holding a rope wrapped around a cylinder, not just a man free falling. So you would have to consider the rotating cylinder under the torque created by the man gravity force.
Let g = 10m/s2
T = mgd =75*10*0.4 = 300 N.m
The from the mass moments inertial of the solid cylinder:
we can calculate the angular acceleration of the cylinder:
then translate that to acceleration:
c) if the mass of the rope is not neglected, that means the force of gravity increases as the rope unwrapping around the cylinder, so the torque increases. Also the moment of inertial of the rope-cylinder system decreases due to rope unwrapping. In the end, the angular acceleration is no longer constant, but increasing.
Answer:Health
Throughout her work with radium, Marie was unaware of the effects of radioactivity exposure on the body. In her lab, she would keep tubes of radium in her pocket. [3] She began to suspect that radium negatively impacted health when one of her fellow researchers died of a blood disease, and then a few years later her personal assistant died of a blood disease. Even though she suspected that radium exposure was bad for her health, she did very little to monitor her own blood. In 1932, she broke her wrist and the break took much longer to heal than it should have. She then began to notice that her vision was deteriorating and radiation burns on her fingers were becoming more and more painful. Some days she felt too ill to even go to the lab, and finally on July 4, 1934, Marie died from aplastic anemia. [1]
Radium Exposure Treatments
Marie suspected that her health was being negatively impacted by radium exposure, but did nothing about it, most likely because there weren't any effective treatments for radium poisoning yet. At the time, scientists knew that radium was metabolized like calcium. In an attempt to remove it from the system, they manipulated calcium intake. [4] This caused little to no improvements, so parathyroid hormone was added to the treatment. Again, there was some reduction of radium, but not a significant amount. It wasn't until after Marie's death that they realized once radium is in the bones, it is extremely difficult to extract. The lack of therapies for radium exposure may explain why Marie just ignored her symptoms, because she was fully aware of her fate. [4]
© Jenna Gray. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
Explanation:
Base on my research is that in order to balance an equation, you need to make sure that both the reactant and the product of the equation is equal. So base on the problem the product has dihydrogen monoxide. So to make sure this equation to be in balanced you need to add coefficients 2 to the oxygen to make it dioxygen on the left side. The balanced equation is now CH4 + 2O2 = CO2 + 2H2O
Answer:
very little force causes friction
Explanation:
