When you blow some air above a paper strip, the paper, rises. This is because 1.) the air above the paper moves faster and the pressure is lower 2.) the air above moves faster and the pressure is higher 3.) the air above the paper moves faster and the pressure remains constant 4.) the air above the paper moves slower and the pressure is higher 5.) the air above the paper moves slower and the pressure is lower
Answers
The correct option is option (1)
The faster movement of air on the upper surface of the paper creates lower pressure above the paper.
Pressure difference:
The movement of air is always from a region of higher pressure to a region of lower pressure.
As we blow air above the paper strip a low pressure is created above the strip due to the fast movement or high speed of the air. And the pressure below the strip is higher in comparison to the pressure above since the air below is not moving.
So, due to the pressure difference, a force is generated on the paper strip by the air from the lower surface to the upper surface.
Learn more about pressure difference:
This is happened because "the air" above "moves faster" and "the pressure" is "lower".
Option: 1
Explanation:
Air movement take place from the region where air pressure is more than the region where the pressure is low. When we "blow" air above the "paper strip" paper rises because "low pressure" is created above the strip as high speed winds always travel with reduced air pressure. Hence due to higher air pressure below the strip, it is pushed upwards. This difference in pressure results into fast air moves. This happen because "speed" of the wind depends on "the difference between the pressures" of the air in the two regions.
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Answers
Answer:
R = 8.94 10⁻² Ω/m, R_sp / R_total = 44.8
Explanation:
The resistance of a metal cable is
R = ρ L / A
The area of a circle is
A = π R²
The resistivity of copper is
ρ = 1.71 10⁻⁸ ohm / m
Let's calculate
R = 1.71 10⁻⁸ 4.27 / (π (0.51 10⁻³)²)
R = 8.94 10⁻² Ω/m
Each bugle needs two wire, phase and ground
The total wire resistance is
R_total = 2 R
R_total = 17.87 10⁻² Ω
Let's look for the relationship between the resistance of the bugle and the wire
R_sp / R_total = 8 / 17.87 10⁻²
R_sp / R_total = 44.8
Final answer:
The resistance of the speaker wire can be calculated using the formula for the resistance of a wire, taking into account the resistivity of copper, the length and thickness of the wire, and whether a single or pair of wires is used.
Explanation:
The question is asking you to find the minimum resistance of a copper wire given its diameter and length, plus the resistance of the speaker it's connected to. Resistance of a wire is calculated using the formula R=ρL/A, where R is the resistance, ρ (rho) is the resistivity of the material (in this case, copper), L is the length of the wire, and A is the cross-sectional area of the wire.
First, you need to find the area of the 0.51 mm diameter wire. The area (A) of a wire is given by the formula π(d/2)^2 where d is the diameter of the wire. After calculating the area, use the formula R=ρL/A to calculate the resistance. For copper wire at 20°C, ρ is approximately 1.68 × 10^-8 Ω·m. Substituting these values into the formula will give you the resistance of the wire in ohms.
Note: you may need to consider whether you have just a single wire or a pair, since two wires are typically required to connect a speaker. If a pair is used, each wire will carry half the current, which affects the total resistance.
Learn more about Electric Resistance here:
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Answers
Answer:
the statements, the correct one is A
a downward force of gravity and an upward force exerted by the surface
Explanation:
When the disc is hit, a thrust force is exerted in the direction of movement, at the moment the disc moves this force loses contact and becomes zero.
When the movement is already established there are two main forces: gravity that acts downwards and the reaction force to the support of the disk called normal that acts upwards.
As it is not mentioned that there is friction, this force that opposes the movement is zero.
Analyzing the statements, the correct one is A
Answers
Answer:
The answer is below
Explanation:
a) Using the formula:
b)
B. 1700 Hz, 5100 Hz
C. 3400 Hz, 6800 Hz
D. 3400 Hz, 10,200 Hz
Answers
Answer:
B. 1700 Hz, 5100 Hz
Explanation:
Parameters given:
Length of ear canal = 5.2cm = 0.052 m
Speed of sound in warm air = 350 m/s
The ear canal is analogous to a tube that has one open end and one closed end. The frequency of standing wave modes in such a tube is given as:
f(m) = m * (v/4L)
Where m is an odd integer;
v = velocity
L = length of the tube
Hence, the two lowest frequencies at which a dog will have increased sensitivity are f(1) and f(3).
f(1) = 1 * [350/(4*0.052)]
f(1) = 1682.69 Hz
Approximately, f(1) = 1700 Hz
f(3) = 3 * [350/(4*0.052)]
f(3) = 5048 Hz
Approximately, f(3) = 5100 Hz
b) Calculate the flow speed in the bathroom.
c) What is algebraic expression for the pressure in the bathroom?
d) Calculate the water pressure in the bathroom. Report your answer in the (atm) unit.
Answers
Answer:
A) A₁ V₁ = A₂V₂
B) V₂ = 19 m /s
C) P₁ + (1/2)ρv₁² = P₂ + (1/2)ρv₂² + (h₂ - h₁ )ρg
D) P₂ = 1.88 atm
Explanation:
A) From the piaget's theory of conservation of volume, we can calculate the rate of flow of water from;
A₁ V₁ = A₂V₂
Where;
A₁ and A₂ are area of cross section V₁ and V₂ are velocity of flow at two places along pipe.
B) Using the formula given in A above, we obtain;
π x 1.2² x 4.75 = π x 0.6² x V₂
V₂ x 0.36 = 6.84
V₂ = 6.84/0.36
V₂ = 19 m /s
c ) To find pressure we shall apply Bernoulli's theorem in fluid dynamics;
P₁ + (1/2)ρv₁² = P₂ + (1/2)ρv₂² + (h₂ - h₁ )ρg
Where;
P₁ and P₂ are pressure at ground and second floor respectively
v₁ and v₂ are velocity at ground and second floor respectively
h₁ and h₂ are height at ground and second floor respectively ρ is density of water.
Thus, plugging in the relevant values to obtain;
4.1 x 10⁵ + (1/2 x 1000 x 4.75²) = P₂ + (1/2 x 1000 x 19²) + (5.2 x 1000 x 9.8)
(4.1 x 10⁵) + (0.11 x 10⁵) = P₂ + (1.8 X 10⁵) + (0.51 X 10
P₂ = 1.9 X 10⁵ N/m² = 1.88 atm
Answers
The block slide on the horizontal surface is "24.99 m" far.
According to the question,
- Vertical height = 5.0 m
- Coefficient of friction = 0.20
Let,
- The time taken be "t".
Now,
→
By substituting the values, we get
The final velocity will be:
→
Now,
→
hence,
The distance will be:
→
Thus the above approach is right.
Learn more about friction here:
Answer:
The block slides on the horizontal surface 25 m before coming to rest.
Explanation:
Hi there!
For this problem, we have to use the energy-conservation theorem. Initially, the block has only gravitational potential energy (PE) that can be calculated as follows:
PE = m · g · h
Where:
m = mass of the block.
g = acceleration due to gravity.
h = height at which the block is located.
As the block starts to slide down the track, its height diminishes as well as its potential energy. Due to the conservation of energy, energy can´t disappear, so the loss of potential energy is compensated by an increase of kinetic energy (KE). In other words, as the block slides, the potential energy is converted into kinetic energy. The equation of kinetic energy is the following:
KE = 1/2 · m · v²
Where:
m = mass of the block.
v = speed of the block.
Then, at the bottom of the ramp, the kinetic energy of the block will be equal to the potential energy that the block had at the top of the ramp.
Initial PE = KE at the bottom
When the block starts sliding horizontally, friction force does work to stop the block. According to the energy-work theorem, the change in the kinetic energy of an object is equal to the net work done on that object. In other words, the amount of work needed to stop the block is equal to its kinetic energy. Then, the work done by friction will be equal to the kinetic energy of the block at the bottom, that is equal to the potential energy of the block at the top of the track:
initial PE = KE at the bottom = work done by friction
The work done by friction is calculated as follows:
W = Fr · Δx
Where:
W = work
Fr = friction force.
Δx = traveled distance.
And the friction force is calculated as follows:
Fr = μ · N
Where:
μ = coefficient of friction.
N = normal force.
Since the block is not accelerated in the vertical direction, in this case, the normal force is equal to the weight (w) of the block:
Sum of vertical forces = ∑Fy = N - w = 0 ⇒N = w
And the weight is calculated as follows:
w = m · g
Where m is the mass of the block and g the acceleration due to gravity.
Then, the work done by friction can be expressed as follows:
W = μ · m · g · Δx
Using the equation:
intial PE = work done by friction
m · g · h = μ · m · g · Δx
Solving for Δx
h/μ = Δx
5.0 m / 0.20 = Δx
Δx = 25 m
The block slides on the horizontal surface 25 m before coming to rest.