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3 years ago

house current is 120 volts. if a light bulb runs a current of 0.5 amps, what is the resistance of the bulb

1 answer:

6 0

Ohm's Law tells the relationship between voltage, current, and resistance.
It can be written in three different ways, depending on which ones you know,
and which one you want to find.

Here's the one we need:

   Resistance = (voltage) divided by (current)

   = (120 V) / (0.5 Amp)

   =    240 ohms .

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Two speakers separated by a distance of 4.40 m emit sound. The speakers have opposite phase. A person listens from a location 3.

Hoochie [10]

Answer:

f = 147.21 Hz

Explanation:

In order to have a destructive interference, as the source emit in opposite phases, the path difference between the distance to the person, measured in a straight line from the speakers, must be equal to an integer number of wavelengths.

We need to know the distance from the listener to the other speaker, located 4.4 m from the one which is directly in front of him, which we can find using Pythagorean theorem, as follows:

l₂ = √(3)²+(4.4)² = 5.33 m

The difference in path will be, then:

d = l₂-l₁ = 5.33 m - 3.00 m = 2.33 m

For the lowest frequency that gives destructive interference, the wavelength will be highest possible, which happens when the distance is just one wavelength.

⇒ d = λ = 2.33 m

In any wave, there exists a fixed relationship between speed, frequency and wavelength, as follows:

v = λ*f Κ ⇒ f = v/λ

Taking the speed of sound as 343 m/s, and solving for f, we get:

f= 343 m/s / 2.33 m = 147.21 Hz

3 0

3 years ago

In a crash test, a 2,500 kg car hits a concrete barrier at 13 m/s2 calculate the amount of force at which the car strikes the ba

Marta_Voda [28]

Answer:

32500N

Explanation:

Data obtained from the question include:

m (mass) = 2500 kg

a (acceleration) = 13 m/s2

F (force) =?

Force is the product of mass and acceleration. It is represented mathematically as:

Force = mass x acceleration

F = m x a

With the above formula, the force with which the car strikes the barrier can be obtained as follow:

F = m x a

F = 2500 x 13

F = 32500N

Therefore, the car will strike the barrier with a force of 32500N

8 0

3 years ago

Read 2 more answers

What is the distance covered by a Freely falling object 5 seconds after being dropped ? After 6 seconds?

mario62 [17]

This year is 60 years since I learned this stuff, and one of the things I always remembered is the formula for the distance a dropped object falls:

D = 1/2 A T²

Distance = (1/2) (acceleration) (time²)

The reason I never forgot it is because it's SO useful SO often. You really should memorize it. And don't bury it too deep in your toolbox ... you'll be needing it again very soon. (In fact, if you had learned it the first time you saw it, you could have solved this problem on your own today.)

The problem doesn't tell us what planet this is happening on, so let's make it easy and just assume it's on Earth. Then the 'acceleration' is Earth gravity, and that's 9.8 m/s² .

In 5 seconds:

D = 1/2 A T²

D = (1/2) (9.8 m/s²) (5 sec)²

D = (4.9 m/s²) (25 sec²)

D = 122.5 meters

In 6 seconds:

D = 1/2 A T²

D = (1/2) (9.8 m/s²) (6 sec)²

D = (4.9 m/s²) (36 sec²)

D = 176 meters

5 0

3 years ago

An object with a mass of 70 kilograms is supported at a height of 8 meters above the ground, what's the potential energy of the

Olegator [25]

Answer:

5488 Joules

Explanation:

Use the formula for the potential energy:

$E_p = mgh = 70kg\cdot 9.8\frac{m}{s^2}\cdot 8m = 5488 J$

6 0

3 years ago

A pendulum is used in a large clock. The pendulum has a mass of 2 kg. If the pendulum is moving at a speed of 2.9 m/s when it re

Rufina [12.5K]

This is a classic example of conservation of energy. Assuming that there are no losses due to friction with air we'll proceed by saying that the total energy mus be conserved.
$E_m=E_k+E_p$
Now having information on the speed at the lowest point we can say that the energy of the system at this point is purely kinetic:
$E_m=Ek=\frac{1}{2}mv^2$
Where m is the mass of the pendulum. Because of conservation of energy, the total energy at maximum height won't change, but at this point the energy will be purely potential energy instead.
$E_m=E_p$
This is the part where we exploit the Energy's conservation, I'm really insisting on this fact right here but it's very very important, The totam energy Em was
$E_M=\frac{1}{2}mv^2$
It hasn't changed! So inserting this into the equation relating the total energy at the highest point we'll have:
$E_p=mgh=E_m=\frac{1}{2}mv^2$
Solving for h gives us:
$h=\frac{v^2}{2g}.$
It doesn't depend on mass!

4 0

3 years ago

Read 2 more answers