The battery for a certain cell phone is rated at 3.70 V. According to the manufacturer it can produce math]3.15 \times 10^{4} J[
1 answer:
Answer:
The average current that this cell phone draws when turned on is 0.451 A.
Explanation:
Given;
voltage of the phone, V = 3.7 V
electrical energy of the phone battery, E = 3.15 x 10⁴ J
duration of battery energy, t = 5.25 h
The power the cell phone draws when turned on, is the rate of energy consumption, and this is calculated as follows;
where;
P is power in watts
E is energy in Joules
t is time in seconds
The average current that this cell phone draws when turned on:
P = IV
Therefore, the average current that this cell phone draws when turned on is 0.451 A.
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Answer:
a) The average velocity is v = (60 km/h ; 0)
b) The average speed is 60 km/h
Explanation:
The velocity is a vector that has a magnitude and direction. The average speed is the distance traveled over time without taking into account the direction of the motion.
a)The average velocity is calculated as the displacement over time:
v = Δx/Δt
where
v = velocity
Δx = final position - initial position = traveled distance relative to the center of the reference system.
Δt = final time - initial time (initial time is usually = 0)
We know that the displacement is 84 km but we do not know the time. It can be calculated from the two parts of the trip.
In part 1:
v = 45 km/h = 42 km / t
t = 0.93 h
In part 2:
v = 90 km/h = 42 km / t
t = 42 km / 90 km/h
t = 0.47 h
The time of travel is 0.47 h + 0.93 h = 1.4 h
The average velocity will be:
v = 84 km / 1.4 h = 60 km/h
Expressed as a vector in a 2-dimension plane:
v = (60 km/h; 0)
b) The average speed is calculated as the distance traveled over time. Note that in this case, the distance is equal to the displacement since the direction of the motion is always in one direction. But if the direction of the second part of the trip would have been the opposite to the direction of the first part, the displacement would have been 0 (final position - initial position = 0, because final position = initial position), then, the average velocity would have been 0. In change, the average speed would have been the distance traveled (84 km, 42 km in one direction and 42 km in the other) over time.
Then:
average speed = 84 km / 1.4 h = 60 km/h
c) see attached figure.
Answer:
The charge density in the system is
Explanation:
To solve this problem it is necessary to keep in mind the concepts related to current and voltage through the density of electrons in a given area, considering their respective charge.
Our data given correspond to:
We need to asume here the number of free electrons in a copper conductor, at which is generally of
The equation to find the current is
Where
I =Current
V=Velocity
A = Cross-Section Area
e= Charge for a electron
n= Number of free electrons
Then replacing,
Now to find the linear charge density, we know that
Where:
I: current intensity
Q: total electric charges
t: time in which electrical charges circulate through the conductor
And also that the velocity is given in proportion with length and time,
The charge density is defined as
Replacing our values
Therefore the charge density in the system is
Answer:
<em>radius of the loop = 7.9 mm</em>
<em>number of turns N ≅ 399 turns</em>
Explanation:
length of wire L= 2 m
field strength B = 3 mT = 0.003 T
current I = 12 A
recall that field strength B = μnI
where n is the turn per unit length
vacuum permeability μ = = 1.256 x 10^-6 T-m/A
imputing values, we have
0.003 = 1.256 x 10^−6 x n x 12
0.003 = 1.507 x 10^-5 x n
n = 199.07 turns per unit length
for a length of 2 m,
number of loop N = 2 x 199.07 = 398.14 ≅ <em>399 turns</em>
since there are approximately 399 turns formed by the 2 m length of wire, it means that each loop is formed by 2/399 = 0.005 m of the wire.
this length is also equal to the circumference of each loop
the circumference of each loop =
0.005 = 2 x 3.142 x r
r = 0.005/6.284 = = 0.0079 m =<em> 7.9 mm</em>