All categories

2 years ago

How much does it cost to operate a 25-w soldering iron for 8.0 hours if energy costs 8.0¢/kwh?

1 answer:

6 0

The power P is defined as the energy E per unit of time t:
$P= \frac{E}{t}$
In our problem, the power is P=25 W and the total time is t=8.0h, so we can calculate the total energy used during this time:
$E=Pt=(25 W)(8.0 h)=200 Wh=0.2 kWh$
The energy costs 8€ per each kwh, so we can write the following proportion:
$8€: 1kwh = x:0.2 kWh$
where x is the price corresponding to 0.2 kWh. Solving the proportion we find x:
$x= \frac{(8€)(0.2 kWh)}{1kWh}=1.6$ €

You might be interested in

Four students were loading boxes of food collected during a food drive. The force that each student exerted while lifting and th

Fudgin [204]

Answer:

it is B

Explanation:

Edge2020

7 0

2 years ago

Read 2 more answers

An organ pipe open at both ends has a radius of 4.0 cm and a length of 6.0 m. what is the frequency (in hz) of the third harmoni

Marysya12 [62]

When air is blown into the open pipe,

L = $\frac{nλ}{2}$

where nis any integral number 1,2,3,4 etc. and λ is the wavelength of the oscillation

⇒λ= $\frac{2L} {n}$

Note here that n=1 is for fundamental, n=2 is first harmonic and so on..

⇒ third harmonic will be n=4

Given L=6m, n=4, solving for λ we get:

λ= $\frac{(2)*(6)}{4}$ =3m

Relationship of frequency(f), velocity of sound (c) and wavelength(λ) is:

c=f.λ Or f= $\frac{c}{λ}$

⇒f= $\frac{344}{3}$

≈115 Hz

8 0

2 years ago

Which of the following statements characterizing types of waves are true?

Tasya [4]

Answer:

a and b.

Explanation:

In general types of wave

1. Transverse wave :

In these waves particle are vibrate perpendicular to motion of waves.

Ex : Electromagnetic wave , Radio wave .

2. Longitudinal wave :

In these waves particle are vibrate along the motion of waves.

Ex : Sound wave

Mechanical wave :

1 .These are transverse wave or Longitudinal wave or combination of them .

2.These waves required medium for propagation.

3. The particle are vibrate perpendicular to motion of waves.

So the option a and b are correct.

7 0

2 years ago

The 8 kg block is then released and accelerates to the right, toward the 2 kg block. The surface is rough and the coefficient of

natita [175]

Answer:

3.258 m/s

Explanation:

k = Spring constant = 263 N/m (Assumed, as it is not given)

x = Displacement of spring = 0.7 m (Assumed, as it is not given)

$\mu$ = Coefficient of friction = 0.4

Energy stored in spring is given by

$U=\dfrac{1}{2}kx^2\\\Rightarrow U=\dfrac{1}{2}\times 263\times 0.7^2\\\Rightarrow U=64.435\ J$

As the energy in the system is conserved we have

$\dfrac{1}{2}mv^2=U-\mu mgx\\\Rightarrow v=\sqrt{2\dfrac{U-\mu mgx}{m}}\\\Rightarrow v=\sqrt{2\dfrac{64.435-0.4\times 8\times 9.81\times 0.7}{8}}\\\Rightarrow v=3.258\ m/s$

The speed of the 8 kg block just before collision is 3.258 m/s

7 0

2 years ago

3. A very light bamboo fishing rod 3.0 m long is secured to a boat at the bottom end. It is

netineya [11]

The image in the attachment describes the situation of the fishing rod.

Answer: F = 10.8 N

Explanation: The image shows a fishing rod attached to an axis. To stay in equilibrium, Torque must be equal for the force of magnitude 18N and for the unknow force.

Torque (τ) is a measure of a force's tendency to cause rotation and, in physics, defined as:

τ = F.r.sin(θ)

F is the force acting on the object;

r is distance between where the torque is measured to where the force is applied;

θ is the angle between F and r;

For the fishing rod:

$\tau_{1} = \tau_{2}$