Answer:
1.87 A
Explanation:
τ = mean time between collisions for electrons = 2.5 x 10⁻¹⁴ s
d = diameter of copper wire = 2 mm = 2 x 10⁻³ m
Area of cross-section of copper wire is given as
A = (0.25) πd²
A = (0.25) (3.14) (2 x 10⁻³)²
A = 3.14 x 10⁻⁶ m²
E = magnitude of electric field = 0.01 V/m
e = magnitude of charge on electron = 1.6 x 10⁻¹⁹ C
m = mass of electron = 9.1 x 10⁻³¹ kg
n = number density of free electrons in copper = 8.47 x 10²² cm⁻³ = 8.47 x 10²⁸ m⁻³
= magnitude of current
magnitude of current is given as


= 1.87 A
1. Always be the bigger person
2. Violence is never the answer
3. Don’t fight fire with fire
If the net force on a block is zero, the block will move at constant velocity
Explanation:
We can answer this question by applying Newton's second law of motion, which states that the net force on an object is equal to the product between its mass and its acceleration:
(1)
where
is the net force on the object
m is its mass
a is its acceleration
In this problem, we have a block, and the net force on it is zero:

According to eq.(1), this also implies that

So, the acceleration of the block is zero.
However, acceleration is the rate of change of velocity of a body:

where
is the change in velocity in a time of
. Since the acceleration is zero, this means that
, and therefore the velocity of the object is constant.
Learn more about Newton's second law:
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The answer is D, the brain actually stops growing around age 18
Answer:
Milimeters
Explanation:
This kind of question must be checked with everyday elements, in this way we will analyze each of the options until we reach the appropriate:
kilograms can not be because this unit serves to measure the mass not the length.
kilometers (km) is a unit of length, but however it does not serve for this measurement since a km is equivalent to 1000 meters, therefore measuring the length of a shoe with a ruler measuring 1000 meters is very impractical.
milliliters is a unit of volume, and can often be found in the measurement of volume content of liquids, for example 700 milliliters of milk or 1000 milliliters of water. Therefore it is impractical to measure a shoe with a unit of volume.
In this way the way to measure a shoe correctly is using a ruler or measuring instrument graduated in millimeters.