Answer:
I = 4.75 A
Explanation:
To find the current in the wire you use the following relation:
(1)
E: electric field E(t)=0.0004t2−0.0001t+0.0004
ρ: resistivity of the material = 2.75×10−8 ohm-meters
J: current density
The current density is also given by:
(2)
I: current
A: cross area of the wire = π(d/2)^2
d: diameter of the wire = 0.205 cm = 0.00205 m
You replace the equation (2) into the equation (1), and you solve for the current I:
Next, you replace for all variables:
hence, the current in the wire is 4.75A
Answer:
<em>The acceleration of the racecar is</em> 
Explanation:
<u>Uniformly Accelerated Motion</u>
It's a type of motion in which the velocity of an object changes by an equal amount in every equal period of time.
Following the definition above, the acceleration is defined as:
Where a is the constant acceleration, vo the initial speed, vf the final speed, and t the time.
The racecar goes from vo=18.5 m/s to vf=46.1 m/s in t=2.47 seconds, thus the acceleration is:
The acceleration of the racecar is
Most of the question 1 is chopped off so I'll try my best to answer.
1ai) In a telephone, the sound is converted into electrical signals before being sent through the wire before converted back into sound.
1aii) Sound travels by the collision between particles. In solids, the particles are closely packed (as compared to air molecules) and thus collide with their neighbors quickly after being disturbed, allowing for sound to be passed on at a faster rate.
b) Can't help much on this one.
Answer:
B. Conductivity.
Explanation:
Conductivity is the quantity of heat passing per second through a slab of unit cross-sectional area when the temperature gradient between the two faces is unity when put in heat.
