Which of the following circuits can be used to measure the resistance of the heating element, shown as a resistor in the diagram
s below?
1 answer:
In order to measure the resistance in the circuit, we need to know the voltage V and the current I in the circuit, this way we can calculate the resistance using the formula:
In order to calculate the current, we can use an amperemeter that must be in series with the circuit, this way it will not affect the circuit.
And in order to calculate the voltage, we can use a voltmeter that must be in parallel with the resistance, this way it will not affect the circuit.
The correct option that shows an amperemeter in series and a voltmeter in parallel is the fourth option.
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The key to solve this problem is the conservation of momentum. The momentum of an object is defined as the product between the mass and the velocity, and it's usually labelled with the letter :
The total momentum is the sum of the momentums. The initial situation is the following:
(it's not written explicitly, but I assume that the 5-kg object is still at the beginning).
So, at the beginning, the total momentum is
At the end, we have
(the mass obviously don't change, the new velocity of the 15-kg object is 1, and the velocity of the 5-kg object is unkown)
After the impact, the total momentum is
Since the momentum is preserved, the initial and final momentum must be the same. Set an equation between the initial and final momentum and solve it for , and you'll have the final velocity of the 5-kg object.