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White raven [17]
3 years ago
11

How long does it take for a 3.5 kW electric water heater to heat 40 kg of water? from 20 ° C to 75 ° C? The specific heat capaci

ty of water is 4190 J/kgK PLEASE HURRY ITS A TEST​
Physics
1 answer:
iren [92.7K]3 years ago
4 0

Answer:

2633.7 s

Explanation:

From the question,

Heat lost by the water heater = Heat gained by the water

Applying,

P = cm(t₂-t₁)/t.................. Equation 1

Where P = power of the heat, c = specific heat capacity of water, m = mass of water, t₁ = initial temperature, t₂ = final temperature, t = time

make t the subject of the equation

t = cm(t₂-t₁)/P.............. Equation 2

From the question,

Given: c = 4190 J/kgK, P = 3.5 kW = 3500 W, m = 40 kg, t₁ = 20°C, t₂ = 75°C

Substitute these values into equation 2

t = 4190×40(75-20)/3500

t = 9218000/3500

t = 2633.7 s

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Nature selects organisms with specific ______to survive and reproduce
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Answer:

Nature selects organisms with specific heritable traits to survive and reproduce

Explanation:

The Evolution Theory by natural selection dictates that organisms with specific inherited characteristics have better survival chances in the new environment.

Inheriting positive traits such as resistance to a certain disease will improve the survival chances of the organism to enable it reproduce and pass that gene to the next generation.

6 0
3 years ago
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Which is the best definition to describe a transfer of energy?
MissTica

Answer:

a

Explanation:

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2 years ago
A spring stretches by 0.0208 m when a 3.39-kg object is suspended from its end. How much mass should be attached to this spring
sashaice [31]

Answer:

COMPLETE QUESTION

A spring stretches by 0.018 m when a 2.8-kg object is suspended from its end. How much mass should be attached to this spring so that its frequency of vibration is f = 3.0 Hz?

Explanation:

Given that,

Extension of spring

x = 0.0208m

Mass attached m = 3.39kg

Additional mass to have a frequency f

Let the additional mass be m

Using Hooke's law

F= kx

Where F = W = mg = 3.39 ×9.81

F = 33.26N

Then,

F = kx

k = F/x

k = 33.26/0.0208

k = 1598.84 N/m

The frequency is given as

f = ½π√k/m

Make m subject of formula

f² = ¼π² •(k/m

4π²f² = k/m

Then, m4π²f² = k

So, m = k/(4π²f²)

So, this is the general formula,

Then let use the frequency above

f = 3Hz

m = 1598.84/(4×π²×3²)

m = 4.5 kg

4 0
3 years ago
Describe the initial horizontal and vertical velocity of a horizontally launched projectile on Earth, as well as what happens to
Jobisdone [24]

Answer:

Explained below

Explanation:

To explain this, let's consider a tennis ball being launched from the top of a very high building.

Now, if the tennis ball is launched horizontally without any upward angle but with an initial velocity of 10 m/s. In this motion, If there is no gravity, the tennis ball would continue in motion at that same speed of 10 m/s in the horizontal direction. However, in reality, gravity causes the tennis ball to accelerate downwards at a rate of 9.8 m/s for every second. This implies that the vertical velocity component is changing at the rate of 9.8 m/s every second.

Thus, after 1 second, horizontal velocity component will remain 10 m/s and vertical component will be 9.8 m/s × 1 = 9.8 m/s downwards.

Also, after 2 seconds, the vertical velocity component will remain 10 m/s, however the vertical component will now be 9.8 × 2 = 19.6 m/s downwards.

Same procedure is repeated as t increases by 1 second.

5 0
3 years ago
Sam's job at the amusement park is to slow down and bring to a stop the boats in the log ride. If a boat and its riders have a m
shutvik [7]

Answer:

Sam will do 1152 J of work to stop the boat

Explanation:

Work: This is defined as the product of force and distance, the S.I unit of work is Joules. At any point in science, during calculation Energy and worked can be interchange because they have the same unit.

E = W = 1/2mv²................ Equation 1

Where E = energy, W = work, m = mass, v = velocity.

Given: m = 900 kg, v = 1.6 m/s

Substituting these values into equation 1

W = 1/2(900)(1.6)²

W = 450×2.56

W = 1152 J.

Therefore Sam will do 1152 J of work to stop the boat

7 0
3 years ago
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