Here is your answer:
1. A alternating current is a current "is an electric current which periodically reverses direction." A direct current is a "<span>current which flows only in one direction."
2. They are alike because both are "they both are able to travel in different directions." How they are not alike is that a "alternating current travels in a reverse direction but a direct current can only travel in one direction each current."
Hope this helps!</span>
Answer:
H / R = 2/3
Explanation:
Let's work this problem with the concepts of energy conservation. Let's start with point P, which we work as a particle.
Initial. Lowest point
Em₀ = K = 1/2 m v²
Final. In the sought height
= U = mg h
Energy is conserved
Em₀ =
½ m v² = m g h
v² = 2 gh
Now let's work with the tire that is a cylinder with the axis of rotation in its center of mass
Initial. Lower
Em₀ = K = ½ I w²
Final. Heights sought
Emf = U = m g R
Em₀ =
½ I w² = m g R
The moment of inertial of a cylinder is
I = 
+ ½ m R²
I= ½ + ½ m R²
Linear and rotational speed are related
v = w / R
w = v / R
We replace
½ w² + ½ m R² w² = m g R
moment of inertia of the center of mass
= ½ m R²
½ ½ m R² (v²/R²) + ½ m v² = m gR
m v² ( ¼ + ½ ) = m g R
v² = 4/3 g R
As they indicate that the linear velocity of the two points is equal, we equate the two equations
2 g H = 4/3 g R
H / R = 2/3
Answer:
A. Normal force is always perpendicular to the area of contact between an object and support.
Explanation:
Normal force is defined as the contact force. If there is no contact between the surfaces, they cannot applies a force which is normal on each other. For e.g, the surfaces of a cubical box and the cart cannot applies a force of normal on each other because of no contact.
If, when there is a contact between two surfaces they applies a normal force on each other, and this force is perpendicular to the each other . This normal force is necessary to prevent object to penetrating into other.
Answer:
L = 5,955 m
Explanation:
For this exercise we must use the relation
R = ρ L / A
where R is the resistance that indicates that it is 1 Ω, the resistivity is taken from the tables ρ = 2.82 10⁻⁸ Ω m, L is the length of the wire and A is the cross section.
As it indicates to us in volume of aluminum to use we divide the two terms by the length
R / L = ρ L / (A L)
the volume of a body is its area times its length, therefore
R / L = ρ L / V
R = ρ L² / V
we clear the length of the wire
L = √ R V /ρ
we reduce the volume to SI units
v = 1 cm³ (1m / 10² cm)³ = 1 10⁻⁶ m
let's calculate
L = √ (1 1 10⁻⁶ / 2.82 10⁻⁸)
L = √ (0.3546 10²)
L = 5,955 m
Answer:
12 m/s
Explanation:
First, find the time it takes for the ball to fall 2.0 m.
y = y₀ + v₀ t + ½ at²
0 = 2.0 + (0) t + ½ (-9.8) t²
0 = 2 − 4.9t²
t = 0.639
Find the velocity needed to travel 7.8 m in that time.
x = x₀ + v₀ t + ½ at²
7.8 = 0 + v₀ (0.639) + ½ (0) (0.639)²
7.8 = 0.639 v₀
v₀ = 12.2
Rounded to two significant figures, the initial velocity is 12 m/s.
