Homework Statement
The amount (A) of cesium-137 remaining after t years is given by
A=A_{0}*2^{\frac{-t}{30.3}}
where A_{0} is the initial amount. In what year will the cesium-137 be 10% of that which was released at the Chernobyl disaster in 1986?
Homework Equations...
Homework Statement
By what factor does the flow rate decrease when a water pipe of diameter 20 cm with a 10 cms^-1 flow rate, splits into two smaller pipes of diameters 11.54 cm and 16.33 cm?
Homework Equations
Q(volume flow rate)=(average velocity)(cross sectional area of flow)
The...
Parabolic Curve Question!
Homework Statement
The parabolic curve described by the cable of a suspension bridge, as shown in the diagram below, is
y=12(x/20-1)^2+3
where x is the distance in metres measured from one end of the
bridge. The deck, or load-bearing portion, is at y = 0 and...
Okay had another try at this one just now..
d=PL/AE
d=(1m*100N)/((1m*〖10〗^(-2))(1*〖10〗^11))
d=100Nm/((1m*1/100)(100000000000))
d=1/1000000
d=1^(-6)
I think that's the right answer, have I missed anything? The cross sectional area got me the first time round, pretty stupid mistake!
edit - I...
Homework Statement
Calculate the deflection at the end of a rod whose dimensions are 1m x 0.1m x 0.1m, when a load of 100N is applied. The modulus of elasticity is given as 1 x 1011 (N/m2)
Homework Equations
d = PL/AE where
d = end deflection of bar in metres (in m)
P = the applied...
can anyone help at all? I have to try to complete a 15 page report on this by the end of the day, and I can't even start writing it without the correct science behind it all =(
I'm now trying to calculate the specific heat of the box using Ethermal=mc(Tfinal-Tinitial), and for some reason I'm getting a higher value for glass than for air, which seems wrong because from what I have read in my textbook gases are meant to have a lower level of heat transfer than solids. I...
okay attempt at solution so far. I decided on a cube shape, sides of 0.5m and a thickness of 0.02m made of glass. The glass has thermal conductivity of 1.4 W/m*k, at a room temperature of 34oC.
q=kA(T1-T2/L)
q=(1.4W/m*k)(1.5m2)(30oC/0.02)
q=3150W=3150J/s
So that gives me the heat...
I have absolutely no experience with anything to do with electric circuits! How would I go about calculating a thermal capacity?
Also, I still don't know what is meant by "A=cross sectional area normal to heat flow (m2)"
edit* and isn't thermal capacity measured in Joules per Kelvin?
the only guidelines for the design are the duration it has to stay below the max temp. I was just going to use 28 degrees C as a starting off point, and then once I can show the relationship between the material used and dimensions of the box on the temperature within the box, come up with a...
Homework Statement
Design a portable container that will keep medicines at around 4 degrees celcius for at least 12 hours.
Homework Equations
Fouriers law, q=kA(T1-T2/L)
Thermal Resistance=L/kA
q=heat transfer rate (in W)
K=thermal conductivity (W/M*degrees C)
A=cross sectional...
Homework Statement
Select a suitable steel rope to suspend a lift from a winch. The weight of the lift is variable as is the weight and diameter of the ropes the lift is suspended from. As an example, I'll use 13mm for the ropes diameter and 0.63kg/m for the rope mass, the total length of the...