Answer:
16613 m/s
Explanation:
Given that
mass of the fly, m = 0.55 g = 0.55*10^-3 kg
Kinetic Energy of the fly, E = 7.6*10^4 J
Speed of the fly, v = ? m/s
We know that the Kinetic Energy is that energy that an object, in this case, the fly, possesses due to its motion.
The Kinetic Energy, KE of any object is represented by the formula
KE = 1/2 * m * v²
If we substitute the values in the relation, we have,
7.6*10^4 = 1/2 * 0.55*10^-3 * v²
v² = (15.2*10^4) / 0.55*10^-3
v² = 2.76*10^8
v = √2.76*10^8
v = 16613 m/s
Thus, the fly would need a speed of 16.6 km/s in order to have a Kinetic Energy of 7.6*10^4 J
Answer:
A) F=-20.16×10⁹N
B) if the distance doubles, force is 4 times smaller.
Explanation:
q1=-28C
q2=5mC=0.005C
d=25cm=0.25m
Electrostatic force between charges: F=k×q1×q2/d², where k is a coefficient that has the value k=9 × 10⁹ N⋅m²⋅C^(-2) for air.
Thus:
F=9×10⁹×(-28)×0.005/0.25²
F=-20.16×10⁹N
The minus sign indicates attraction.
If distance doubles, d1=2×d, then we have 4d² at the denominator and the force is 4 times smaller.
This problem uses the relationships among current
I, current density
J, and drift speed
vd. We are given the total of electrons that pass through the wire in
t = 3s and the area
A, so we use the following equation to to find
vd, from
J and the known electron density
n,
so:

<span>The current
I is any motion of charge from one region to another, so this is given by:
</span>

The magnitude of the current density is:

Being:

<span>
Finally, for the drift velocity magnitude vd, we find:
</span>
Notice: The current I is very high for this wire. The given values of the variables are a little bit odd
To solve this problem we will apply the linear motion kinematic equations. From the definition of the final velocity, as the sum between the initial velocity and the product between the acceleration (gravity) by time, we will find the final velocity. From the second law of kinematics, we will find the vertical position traveled.

Here,
v = Final velocity
= Initial velocity
g = Acceleration due to gravity
t = Time
At t = 4s, v = -30m/s (Downward)
Therefore the initial velocity will be


Now the position can be calculated as,

When it has the ground, y=0 and the time is t=4s,


Therefore the cliff was initially to 41.6m from the ground
Check Khan Academy, they have explanations,notes,videos,quizzes and much more