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3 years ago

Suppose the price of electricity is 12.75 cents per kWºh. What

Physics

1 answer:

adell [148]3 years ago

5 0

Answer:

The difference between the cost of operating LED and incandescent bulb is $5.1

Explanation:

We are given the cost of electricity that is 12.75 cents per kWh. We want to find out the difference in the operating cost of an incandescent and LED bulb for a time period of 2,000 hours.

Since we are not given the rating of the incandescent bulb and LED bulb, we will assume their ratings.

For a light intensity of 250 Lumens;

The average rating of an LED bulb is approximately 5 Watts.

The average rating of an incandescent bulb is approximately 25 Watts.

Now lets find out the kWh of each bulb.

Energy = Power×Time

For LED bulb:

E = 5×2,000 = 10,000 Wh

Divide by 1000 to convert into kWh

E = 10,000/1000 = 10 kWh

Cost = 12.75×10 = 127.5 cents

Cost = $1.27

For Incandescent bulb:

E = 25×2,000 = 50,000 Wh

Divide by 1000 to convert into kWh

E = 50,000/1000 = 50 kWh

Cost = 12.75×50 = 637.5 cents

Cost = $6.37

Difference in Cost:

Difference = $6.37 - $1.27 = $5.1

Therefore, the difference between the cost of operating LED and incandescent bulb is $5.1.

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(15pts) A hungry 12.0 kg fish is coasting from west to east at 75 cm/s when it suddenly swallows a 1 kg fish swimming towards it

faust18 [17]

Answer:

The speed of the big fish after swallowing the small fish is 0.38 m/s.

Explanation:

Consider west to east direction as positive and the opposite direction as negative.

Given:

Mass of big fish (m₁) = 12.0 kg

Initial velocity of big fish (u₁) = 75 cm/s = 0.75 m/s

Mass of small fish (m₂) = 1 kg

Initial velocity of small fish (u₂) = -4 m/s (Direction is opposite to u₁)

After swallowing the small fish, both the fishes move together with same velocity. Let the velocity be 'v'.

So, as there are no effects of drag or any other forces, the given scenario can be considered as a case of inelastic collision where the objects move together with same velocity after collision.

The momentum is conserved in inelastic collision. Therefore,

Initial momentum of the fishes = Final momentum of the fishes

$m_1u_1+m_2u_2=(m_1+m_2)v\\\\v=\dfrac{m_1u_1+m_2u_2}{m_1+m_2}$

Now, plug in the given values and solve for 'v'. This gives,

$v=\frac{12.0\times 0.75+1\times (-4)}{12.0+1}\\\\v=\frac{9-4}{13}\\\\v=\frac{5}{13}=0.38\ m/s$

Therefore, the speed of the big fish after swallowing the small fish is 0.38 m/s

3 0

3 years ago

g stAn experienced spear fisherman sees a small fish swimming in a tidal pool. If the fisherman sees the fish at approximately a

Luba_88 [7]

Answer:

θ = 28.9

Explanation:

For this exercise let's use the law of refraction

n₁ sin θ₁ = n₂ sin θ₂

where we use index 1 for air and index 2 for water where the fish is

sin θ₂ = n₁ / n₂ sin θ₁

in this case the air repair index is 1 and the water 1.33

we substitute

sin θ₂ = 1 / 1.33 sin t 40

sin θ = 0.4833

θ = sin⁻¹ 0.4833

θ = 28.9

5 0

3 years ago

A biologist looking through a microscope sees a bacterium at r⃗ 1=2.2i^+3.7j^−1.2k^μm(1μm=10−6m). After 6.2 s , it's at r⃗ 2=4.6

stiv31 [10]

The Average velocity for the bacterium is 0.75 unit/sec.

Explanation:

The given values are in the vector form

Where,

dS = distance covered

dT = time interval

Now, to calculate distance covered, we have

$|d S|=\sqrt{d S^{2}}$

$d S=r_{2}-r_{1}$

d S=(4.6 i+1.9 k)-(2.2 i+3.7 j - 1.2 k)

d S=(4.6-2.2) i+(0-3.7) j+(1.9+1.2) k

d S=2.4 i-3.7 j+3.1 k

Now, putting these values in the standard formula to evaluate the average velocity, we get;

$v_{a v g}=\frac{|\mathrm{d} S|}{d T}$

$v(a v g)=\frac{|\sqrt{\left\{\left(2.4^{2}\right)+\left(3.7^{2}\right)+\left(3.1^{2}\right)\right\}}|}{7.2}$

As dT=7.2 sec

Now,

Solving the equation, we get;

$v(a v g)=\frac{5.390732789}{7.2}$

$\begin{aligned}&v(a v g)=\frac{5.39}{7.2}\\&v(a v g)=0.748611111\\&v(a v g)=0.75 \text { units / sec }\end{aligned}$

Hence, the average velocity for the bacterium is 0.75 unit/sec.

3 0

3 years ago

Please help me on this

Dafna1 [17]

I’m pretty sure the answer is A

5 0

3 years ago

Two asteroids in outer space collide, and stick together. The mass of each asteroid, and the velocity of each asteroid before th

Naddik [55]

Answer: (2) Use the Momentum Principle.

Explanation:

In fact, it is called the Conservation of linear momentum principle, which establishes the initial momentum $p_{i}$ of the asteroids before the collision must be equal to the final momentum $p_{f}$ after the collision, no matter if the collision was elastic or inelastic (in which the kinetic energy is not conserved).

In this sense, the linear momentum $p$ of a body is defined as:

$p=mV$

Where $m$ is the mass and $V$ the velocity.

Therefore, the useful approach in this situation is option (2).

7 0

3 years ago