Ask question

Ask question

All categories

jek_recluse [69]

3 years ago

12

A 4-kW resistance heater in a water heater runs for 3 hours to raise the water temperature to the desired level. Determine the a

mount of electric energy used in both kWh and kJ.

1 answer:

neonofarm [45]3 years ago

7 0

Answer:

12kWhr

Explanation:

Energy = Power * Time

Power = 4kW

Time = 3hrs

Substitute into the formula

Energy used up = 4kW * 3hrs

Energy used up = 12kWhr

You might be interested in

Alarge plate is fabricated from a steel alloy that has a plane strain fracture toughness of 82.4 MPa m1/2. If the plate is expos

Korvikt [17]

Answer:

minimum length of a surface crack is 18.3 mm

Explanation:

Given data

plane strain fracture toughness K = 82.4 MPa m1/2

stress σ = 345 MPa

Y = 1

to find out

the minimum length of a surface crack

solution

we will calculate length by this formula

length = 1/π ( K / σ Y)²

put all value

length = 1/π ( K / σ Y)²

length = 1/π ( 82.4 $10^{3/2}$ / 345× 1)²

length = 18.3 mm

minimum length of a surface crack is 18.3 mm

4 0

3 years ago

A scientist who wants to study the affects of fertilizer on plants sets up an experiment. Plant A gets no fertilizer, Plant B ge

Solnce55 [7]

Answer: Plant A

Explanation: The control group is participants who do not receive the experimental treatment.

8 0

3 years ago

What are the 3 formulas you can use for vertical motion for a projectile?

klio [65]

I hope this can help you ask me if you need help again

4 0

3 years ago

A 100 kg person rides in an elevator moving at a constant speed of

Airida [17]

Answer:

Explanation:

All this information only applies to the person. There is an extra tension force if we are talking about the elevator, but we are not. Dont forget to apply the units

Acceleration means change in speed or velocity. The elevator is moving at a constant speed of 3 meters. You wont even know you are moving because there is no change in acceleration. It equals 0

The forces ONLY acting on the person would be the force of gravity pulling them down, and the normal force that the elevator is reciprocating from the person standing on it.

Force = mass x acceleration. You have 100 kg and you are accelerating at 0 m/s. The force is 0. Which makes sense because the force of gravity and the net force completely cancel each other out.

8 0

3 years ago

Carbon is allowed to diffuse through a steel plate 15 mm thick. The concentrations of carbon at the two faces are 0.65 and 0.30

beks73 [17]

Answer:

T=575.16K

Explanation:

To solve the problem we proceed to use the 1 law of diffusion of flow,

Here,

$J=-D\frac{\Delta C}{\Delta x}$

$\Delta C$ is the rate in concentration

$\Delta x$ is the rate in thickness

D is the diffusion coefficient, where,

$D= D_0 exp(\frac{Q_d}{RT})$

Replacing D in the first law,

$J=-(D_0 exp(\frac{-Q_D}{RT}))\frac{\Delta }{\Delta x}$

clearing T,

$T=\frac{Q_d}{R*ln(\frac{J*\Delta x}{D_0*\Delta C})}$

Replacing our values

$T=-\frac{80000}{8.31*ln(\frac{(6.2*10^{-7})(-15*10^{-3})}{(1.43*10^{-9})(0.65-0.30)})}$

$T=-\frac{80000}{-138.09}$

$T=575.16K$

4 0

4 years ago