Answer: D
Explanation:
First, we know that the acceleration is defined as the ratio of change of the velocity.
This means that, if we have a change in the velocity, then we also have acceleration.
And by Newton's second law we know that:
F = m*a
Force equals mass times acceleration.
So if we have acceleration different than zero, then we should also have force different than zero.
So we must have a nonzero net force acting on it.
The correct option is D
Answer:
(E) none of these.
Explanation:
first that all we need the meaning of a Watt
<em>" is a unit of power. In the International System of Units (SI) it is defined as a derived unit of 1 </em><em>joule</em><em> per </em><em>second</em><em>,[1] and is used to quantify the rate of </em><em>energy</em><em> transfer." </em>
<em>definition taken from wikipedia.org</em>
now with this concept we have that:
100 W means 100 J/s .Therefore it uses 100 J energy per second
therefore on the answers don't mention this three terms together
Joules, energy and second so the answer must be.
(E) None of these
Answer:
R2 = 10.31Ω
Explanation:
For two resistors in parallel you have that the equivalent resistance is:
(1)
R1 = 13 Ω
R2 = ?
The equivalent resistance of the circuit can also be calculated by using the Ohm's law:
(2)
V: emf source voltage = 23 V
I: current = 4 A
You calculate the Req by using the equation (2):
![R_{eq}=\frac{23V}{4A}=5.75\Omega](https://tex.z-dn.net/?f=R_%7Beq%7D%3D%5Cfrac%7B23V%7D%7B4A%7D%3D5.75%5COmega)
Now, you can calculate the unknown resistor R2 by using the equation (1):
![\frac{1}{R_2}=\frac{1}{R_{eq}}-\frac{1}{R_1}\\\\R_2=\frac{R_{eq}R_1}{R_1-R_{eq}}\\\\R_2=\frac{(5.75\Omega)(13\Omega)}{13\Omega-5.75\Omega}=10.31\Omega](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7BR_2%7D%3D%5Cfrac%7B1%7D%7BR_%7Beq%7D%7D-%5Cfrac%7B1%7D%7BR_1%7D%5C%5C%5C%5CR_2%3D%5Cfrac%7BR_%7Beq%7DR_1%7D%7BR_1-R_%7Beq%7D%7D%5C%5C%5C%5CR_2%3D%5Cfrac%7B%285.75%5COmega%29%2813%5COmega%29%7D%7B13%5COmega-5.75%5COmega%7D%3D10.31%5COmega)
hence, the resistance of the unknown resistor is 10.31Ω
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