Recent content by Pao44445

ok, I give up, is there other way to solve this? some says I can actually use ohm's law directly Vad=(ΣI) (Σ1/R)

Homework Statement find the voltage between a and d and terminal of each batteries Homework Equations Junction Rule and Loop Rule The Attempt at a Solution I got three equation JR : I3 = I1+I2 LR : 45-I3-47I3-34I1 = 0 45-I3-47I3+85-I2-18I2 = 0 I can't solve these...

Homework Statement Initially, copper wire is 20oC then raises the temperature of the wire casing the resistivity up 12%, find the temperature at the final. Homework Equations R=Rref[1+α(T-Tref)] The Attempt at a Solution I am completely confused with this mathematics problem,Stucking with...

it is changed into gas - steam? I know that when then heat reach the phase change, the temperature won't change anymore. How can I apply this with the second equation? Does the change in temperature still the same at 100oC because if there is no change in the temperature the whole equation will...

Homework Statement a copper pot's radius is 12 cm, the thickness is 5 mm. It is placed on the stove for boiling, if the temperature of the stove is 115 oC while the water is 100 oC. How much of water that evaporates per minute Homework Equations ΔQ/Δt = (A)(k)(ΔT) / (L) Q=mcΔT The Attempt...

Never see that equation before :/ I don't know how come Q=mcΔT so I don't actually understand how to use it

oops, sorry. I've edited them and got the same answer 0.45-0.46 K/s I think this is another pure mathematic problem :( really hate this kind of problem.

edited Then Q / (mc)Δt = W/mc (7.4x10-3 W ) / (23x10-6kg)(705 J/kg.K) = 0.46 K/s but how this equation solve the problem?

hmm I don't know if I am correct or not from Q=mcΔT and ΔT/Δt (Q/mc) / Δt = Q / (mc)Δt 7.4x10-3 J / (23x10-6kg)x(705 J/kg.K)x 1 s = 0.46 K/s

Joules per second ? it is just a rate of how much energy was transfer in 1 second, I can't plug this in Q :/

Homework Statement A silicon electric circuit is 23 mg, when electricity flows through the circuit rising the energy by 7.4 mW but this circuit wasn't design for heat ventilation. Find the rate of how much the temperature is rising per second ( ΔT/Δt ) The specific heat of silicon is 705...

Oops, yes my mistake ( I can't edit on my phone right now) I asked my friend, she said the volume of the tank is the same as petrol but why? Or we assume that wall the tank is very thin?

yes, in that case

Homework Statement a steel tank is 70 litres,full of petrol. If a temperature is change from 20o C to 35o, find the increased volume of petrol that overflows (βsteel = 950 x 10-6 ) βpetrol = 36 x 10-6 ) Homework Equations Δv=βv0ΔT The Attempt at a Solution I know that both the steel...

When he converted ω is equal to 2π/T? then it should be ω = (SQRT*k/M) 2π/T = (SQRT*k/M) T = 2π / (SQRT*k/M) am I right? I used this equation an I got about 0.317 s