I'm actually going ahead in the book (DC Circuits) so this isn't really homework but I figured the tag was appropriate....the name of the chapter is Ohm's Law and Watt's Law.
<span>Problem: Calculate the power dissipated in the load resistor, R, for each of the circuits.Circuit (a): V = 10V; I = 100mA; R = ?; Since I know
V and
I use formula
P = IV: P = IV = (100mA)(10V) = 1 W.</span>
The next question is what I'm not sure about:
Question: What is the power in the circuit (a) above if the voltage is doubled? (Hint: Consider the effect on current).
What I did initially was: P = IV = (100mA)(2V) = 2 W
But then I looked at the answer and it said 4 W, then I looked at the Hint again. Then I remembered in the book early on it said "If the voltage increases across a resistor, current will increase."
So question is: When solving problems I have to increase (or decrease) current (I) every time voltage (V) is increased (decreased) in a problem, right? How about the other way around, when increasing current (I), you need to increase voltage (V). I'm pretty sure that's how they got 4 W, but want to make sure before I head to the next section of the book.
P = IV = (200mA)(2V) = 4 W
Option (D) is the correct one.
In order to increase the amount of work done, we need to increase the force applied to the object.
Answer:
Explanation:
A
35 N Small Dog <=======BONE=========> Bigger Dog 42 N
B
Fnet = Large Dog - small dog The forces are subtracted because they are acting in opposite Directions.
Fnet = 42 - 35
Fnet = 7 N
C
m = 2.5 kg
F = 7 N
a = ?
F = m * a
7 = 2.5 a
a = 7 / 2.5
a = 2.8 m/s^2
the acceleration or the next force acting on the body is constant
