If you push in a door one force is directed into the door . according to newtons 3rd law what is the direction of the second force
a. towards the floor
b. towards the ceiling
c. into the door
d. into your hands

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Ответ:

iva60

09.12.2021

Physics

(a) The relationship between the potential difference in a resistor, the current through it and the resistance is given by Ohm's law:
V=IR

where
V is the potential difference
I is the current
R the resistance

Re-arranging the equation, we can calculate the resistance of the lamp when it is on:
$R= \frac{V}{I}= \frac{120 V}{0.75 A}=160 \Omega$

2) When the lamp is hot, its resistance is $160 \Omega$ . When it is cold, its resistance is one fifth of this value, therefore:
$R_c = \frac{1}{5}R= \frac{1}{5}(160 \Omega)=32 \Omega$

3) I assume here the problem is asking for the current through the lamp when the resistance is the value found in part 2) (otherwise the current is the same as point 1). To solve this part of the problem, we can apply again Ohm's law, so we find the new current:
$I= \frac{V}{R_c}= \frac{120 V}{32 \Omega}=3.75 A$

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If you push in a door one force is directed into the door . according to newtons 3rd law what is the direction of the second force a. towards the floor b. towards the ceiling c. into the door d. into your hands