Finding charge, voltage and resistance

AI Thread Summary
The discussion revolves around calculating charge, voltage, and resistance related to a heart defibrillator's operation. To find the charge (Q), the equation Q = I × t can be used, where I is the current (12A) and t is the time (3E-3 seconds). For voltage, the energy (300J) can be related to voltage using the formula E = V × Q, allowing the calculation of voltage once charge is determined. Resistance can be found using Ohm's Law, V = I × R, after calculating voltage. Understanding these relationships is crucial for solving the problems presented.
Kathi201
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A heart defibrillato passes a 12A current through a patient's torso for 3E-3 seconds to restore it to normal beating.
a. How much charge passed through the patient's body?
b. What voltage was used if a total energy of 300J was dissipated? by the current
c. What was the resistance of the path through the person?

For a I know that the current is I and I have the time and I need to figure out Q but I do not have any equations that have all three of those variables in it so I am stuck on what equation to even start with.

For b I am struggling with the same problem. I know that Voltage is equal to the current x resistance but I do not know where the energy comes into place

I know the resistance is the resistivity/A is A the area? How would I figure that out then?


Any help would be appreciated!
 
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Hi Kathi201,

Kathi201 said:
A heart defibrillato passes a 12A current through a patient's torso for 3E-3 seconds to restore it to normal beating.
a. How much charge passed through the patient's body?
b. What voltage was used if a total energy of 300J was dissipated? by the current
c. What was the resistance of the path through the person?

For a I know that the current is I and I have the time and I need to figure out Q but I do not have any equations that have all three of those variables in it so I am stuck on what equation to even start with.

What is the definition of current?

For b I am struggling with the same problem. I know that Voltage is equal to the current x resistance but I do not know where the energy comes into place

What quantity can you find from knowing the energy and the time? How is that related to voltage?

I know the resistance is the resistivity/A is A the area? How would I figure that out then?

Once you find the voltage in part b, what is the relationship between voltage and resistance?
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
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