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4 years ago

Which of the following describes what needs to occur in order to reduce force while doing the same amount of work?

1 answer:

5 0

Among the choices the choices the one that describes what needs to occur in order to reduce force while doing the same amount of work is <span> the distance over which the force is exerted must decrease. The answer is B.

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A heavy meterstick has a mass of 1 kg. When the meterstick is thrown like a spear past you, you measure its momentum to be 2mv.

CaHeK987 [17]

Answer:

Its length is measured to be 0.5 m

Explanation:

From theory of relativity (mass variation), we know that:

m = mo/√(1-v²/c²)

Where, m = relative mass

and, mo = rest mass

The momentum of stick while moving, will be:

P = mv

but, it is given in the form of rest mass as:

P = 2(mo)v

thus, by comparison;

2(mo)v = mv

using value of m from theory of relativity;

2(mo)v = (mo)v/√(1-v²/c²)

√(1-v²/c²) = 1/2 ______ eqn(1)

Now, for relativistic length (L), we have the formula from same theory of relativity;

L = (Lo)√(1-v²/c²)

The rest length (Lo) of meter stick is 1 m, and the remaining term on right side √(1-v²/c²), known as Lorentz Factor, can be given by eqn (1), as equal to 1/2.

Thus,

L = (1 m)(1/2)

4 0

4 years ago

The rate at which heat enters an air conditioned building is often roughly proportional to the difference in temperature between

erma4kov [3.2K]

Answer:

Considering first question

Generally the coefficient of performance of the air condition is mathematically represented as

$COP = \frac{T_i}{T_o - T_i}$

Here $T_i$ is the inside temperature

while $T_o$ is the outside temperature

What this coefficient of performance represent is the amount of heat the air condition can remove with 1 unit of electricity

So it implies that the air condition removes $\frac{T_i}{T_o - T_i}$ heat with 1 unit of electricity

Now from the question we are told that the rate at which heat enters an air conditioned building is often roughly proportional to the difference in temperature between inside and outside. This can be mathematically represented as

$Q \ \alpha \ (T_o - T_i)$

=> $Q= k (T_o - T_i)$

Here k is the constant of proportionality

since 1 unit of electricity removes $\frac{T_i}{T_o - T_i}$ amount of heat

E unit of electricity will remove $Q= k (T_o - T_i)$

$E = \frac{k(T_o - T_i)}{\frac{T_i}{ T_h - T_i} }$

=> $E = \frac{k}{T_i} (T_o - T_i)^2$

given that $\frac{k}{T_i}$ is constant

=> $E \ \alpha \ (T_o - T_i)^2$

From this above equation we see that the electricity required(cost of powering and operating the air conditioner) is approximately proportional to the square of the temperature difference.

Considering the second question

Assuming that $T_i = 30 ^oC$

and $T_o = 40 ^oC$

Hence

$E = K (T_o - T_i)^2$

Here K stand for a constant

$E = K (40 - 30)^2$

=> $E = 100K$

Now if the $T_i = 20 ^oC$

Then

$E = K (40 - 20)^2$

=> $E = 400 \ K$

So from this see that the electricity require (cost of powering and operating the air conditioner)when the inside temperature is low is much higher than the electricity required when the inside temperature is higher

Considering the third question

Now in the case where the heat that enters the building is at a rate proportional to the square-root of the temperature difference between inside and outside

We have that

$Q = k (T_o - T_i )^{\frac{1}{2} }$

$E = \frac{k (T_o - T_i )^{\frac{1}{2} }}{\frac{T_i}{T_o - T_i} }$

=> $E = \frac{k}{T_i} * (T_o - T_i) ^{\frac{3}{2} }$

Assuming $\frac{k}{T_i}$ is a constant

Then

$E \ \alpha \ (T_o - T_i)^{\frac{3}{2} }$

From this above equation we see that the electricity required(cost of powering and operating the air conditioner) is approximately proportional to the square root of the cube of the temperature difference.

4 0

3 years ago

How much kinetic energy a spring that streches 4m would be?

miv72 [106K]

Answer:

Explanation:bjbhfcvvjkkknbnnnm

8 0

3 years ago

The number line shows the starting and ending velocities for ball 1. What’s the change in velocity of ball 1? Calculate the valu

djverab [1.8K]

Answer:

The starting velocity for ball 1 is 1.00 meter/second. Its ending velocity is 0.25 meter/second.

The change in velocity for ball 1 is 0.25 – 1.00 = -0.75 meter/seconds

5 0

3 years ago

Read 2 more answers

3. What is the difference between Synthetic Oil, Semi-Syntheic oil (Blend), High milage motor oil, and conventional motor oil?

MariettaO [177]

Answer:

When evaluating synthetic blends, it's helpful to define the terms “synthetic blend” and “semi-synthetic”. Generally speaking, synthetic blends and semi-synthetic refer to the same thing: an oil that uses a combination of conventional and synthetic base oils in its formulation.

Explanation:

6 0

3 years ago