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Fofino [41]
2 years ago
15

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

Physics
1 answer:
melamori03 [73]2 years ago
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€
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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, <u>Torque</u> must be equal for the force of magnitude 18N and for the unknow force.

<u>Torque </u>(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}

F_{1}.r_{1}.sin(\theta) = F_{2}.r_{2}.sin(\theta)

Assuming part (1) is related to unknown force:

F = \frac{F_{2}.r_{2}.sin(\theta}{r_{1}.sin(\theta) }

Replacing the corresponding values:

F = \frac{18*1.8*sin(30)}{3*sin(30)}

F = \frac{18*1.8}{3}

F = 10.8

<u>The fishing line exert on the the rod a force of </u><u>10.8N</u>.

7 0
2 years ago
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