Which of the following is the best thermal insulator?

Acceleration directed toward the center of a circular path that produces uniform circular motion is

tester [92]

Th answer is Centripetal

4 0

4 years ago

When the body requires an increased blood flow rate in a particular organ or muscle, it can accomplish this by increasing the di

horsena [70]

Answer: The percentage increase in diameter is 19%

Explanation:

Using Poiseuille's law which states that Flow rate , Q = ΔPπr⁴/8ηl

where ΔP is pressure difference, π is a constant, r is the radius which is half of the diameter, η is viscosity of blood, l is length of blood vessel

Let Q₁ be the intitial flow rate, Q₂ the final flow rate,r₁ and r₂ the initial and final radius.

Note: r = d/2, therefore, r₁⁴ = d₁⁴/16 r₂⁴ = d₂⁴/16

Also, Q₂ = 2Q₁, since the flow rate is doubled

Since all factors except diameter is constant, d₂⁴/16 = 2d₁⁴/16

d₂⁴/16 = d₁⁴/8

multiply both sides of the equation by 16

d₂⁴ = 2d₁⁴

taking the fourth root of both sides

d₂ = 1.19*d₁

d₂ - d₁ = 1.19d₁ - d₁

d₂ - d₁ = d₁(1.19 - 1)

d₂ - d₁ = 0.19d₁

d₂ - d₁/d₁ = (0.19d₁/d₁)*100%

(d₂ - d₁/d₁)*100% = 19%

Therefore, the percentage increase in diameter is 19%

3 0

4 years ago

A 1.0-kilogram rubber ball traveling east at 4.0 meters per second hits a wall and bounces back toward the west at 2.0 meters pe

Mrrafil [7]

Answer:

8 J and 2 J

Explanation:

Given that,

Mass of the rubber ball, m = 1 kg

Initial speed of the rubber ball, u = 4 m/s (in east)

Final speed of the rubber ball, v = -2 m/s (in west)

We need to find the kinetic energy of the ball before it hits the wall, the kinetic energy of the ball after it bounces off the wall.

Initial kinetic energy,

$K_i=\dfrac{1}{2}mv^2\\\\K_i=\dfrac{1}{2}\times 1\times (4)^2\\\\K_i=8\ J$

Final kinetic energy,

$K_f=\dfrac{1}{2}mv^2\\\\K_f=\dfrac{1}{2}\times 1\times (2)^2\\\\K_f=2\ J$

So, the initial kinetic energy is 8 J and the final kinetic energy is 2 J.

8 0

3 years ago

Examine the lightbulbs in the circuit below. Write a sentence explaining what would happen if lightbulb A burned out. Repeat thi

tatiyna

If the lightbulb A in the circuit shown in the image burned out, the path for the current to flow is disrupted because one of its terminals is connected direct to the source. So, there will be no current through the lightbulbs B, C, and D, and they will turn off. Similarly it will happen, if the lightbulb D burned out.

If the lightbulb B burned out the current will continue circulating through the lightbulbs A, C, and D, because lightbulb B is connected in parallel. Similarly it will happen, if the lightbulb C burned out.

8 0

4 years ago

Two small plastic spheres are given positive electrical charges. When they are 16.0 cm apart, the repulsive force between them h

katrin2010 [14]

Answer:

a) 7.5425 * 10^-7 C

b) 3.7712 * 10^-7 C ; 1.5085 * 10^-6 C

Explanation:

Part a)

$F_{elect} = \frac{k*q_{1}*q_{2} }{R^2} \\q_{1} = q_{2} = q\\q = \sqrt{\frac{F_{elect} * R^2}{k} }\\ = \sqrt{\frac{0.2 * 0.16^2}{9*10^9} }\\\\ q = 7.5425 * 10 ^(-7) C$

Part b)

$F_{elect} = \frac{k*q_{1}*q_{2} }{R^2} \\q_{1} = 4*q_{2} \\q = \sqrt{\frac{F_{elect} * R^2}{k*4} }\\ = \sqrt{\frac{0.2 * 0.16^2}{4*9*10^9} }\\\\ q_{2} = 3.7712 * 10 ^(-7) C\\\\q_{1} = 1.5085 * 10 ^(-6) C$

3 0

3 years ago