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3 years ago

Energy is A) conserved OB) created only OC) destroyed only OD) created or destroyed

Physics

2 answers:

saw5 [17]3 years ago

5 0

Answer:

Explanation:

Conserving energy produces a higher quality of life. Reduced emissions result in cleaner air quality. In addition, it helps create a healthier planet, or at least helps sustain the resources we already have

Delicious77 [7]3 years ago

4 0

Conserved.

Your explanation is that energy can be neither created, nor destroyed. Therefor, created wouldn’t be an answer, destroyed, or both. A is the only option left.

Hope this helps.

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A force of 5.0 N acts on a 15 kg body initially at rest. Compute the work done by the force in (a) the first, (b) the second, an

Leokris [45]

Answer:

(a) 0.833 j

(b) 2.497 j

(d) 4.995 watt

Explanation:

We have given force F = 5 N

Mass of the body m = 15 kg

So acceleration $a=\frac{F}{m}=\frac{5}{15}=0.333m/sec^2$

As the body starts from rest so initial velocity u = 0 m/sec

(a) From second equation of motion $s=ut+\frac{1}{2}at^2$

For t = 1 sec

$s=0\times 1+\frac{1}{2}\times 0.333\times 1^2=0.1666m$

We know that work done W =force × distance = 5×0.1666 =0.833 j

(b) For t = 2 sec

$s=0\times 2+\frac{1}{2}\times 0.333\times 2^2=0.666m$

We know that work done W =force × distance = 5×0.666 =3.33 j

So work done in second second = 3.33-0.833 = 2.497 j

$s=0\times 3+\frac{1}{2}\times 0.333\times 3^2=1.4985m$

We know that work done W =force × distance = 5×1.4985 =7.4925 j

So work done in third second = 7.4925 - 2.497 -0.833 = 4.1625 j

(d) Velocity at the end of third second v = u+at

So v = 0+0.333×3 = 0.999 m /sec

We know that power P = force × velocity

So power = 5× 0.999 = 4.995 watt

4 0

4 years ago

The area of the pond is approximately equal to the area of a circle with radius 297m. Find the mass of the ice. Answer in kilogr

True [87]

Answer:

mass of the ice is 254980463.8T kg

where T is the value of the thickness omitted in the question.

Explanation:

The ice on Walden Pond is .......... thick. The area of the pond is approximately equal to the area of a circle with radius 297 m. Find the mass of the ice. Answer in kg.

The value of the thickness of the ice T is omitted, but I will show the solution, and the real answer can be gotten by multiplying the final calculated answer here by the thickness of the ice omitted.

Given the radius of the equivalent circle of the ice = 297 m'

the area of the ice can be gotten from area A = $\pi r^{2}$ = $3.142*297^{2}$ = 277152.678 m^2

recall that the density of ice p ≅ 920 kg/m^3

also,

density of ice p = (mass of ice, m) ÷ (volume of ice, v)

i.e p = m/v

and,

m = pv

substituting the value of the density of water p into the equation, we have,

mass of the ice, m = 920v ....... equ 1

The volume of the ice above will be = (area of the ice, A) x (thickness of the ice, T)

i.e v = AT

substituting the value of area A into the equation, we have

v = 277152.678T ......equ 2

substitute value of v into equ 1

mass of the ice, m = 920 x (277152.678T)

mass of the ice, m = 254980463.8T kg

where T is the thickness of the ice

NB: To get the mass, multiply this answer with the thickness T given in the question.

7 0

3 years ago

Water is falling from height of 84 m. If half of the energy of water is converted into heat, the increase in the temperature of

saul85 [17]

Answer:

what are the options??? to choose the answer from?

Explanation:

4 0

3 years ago

Read 2 more answers

You drop two balls from a tower, one of mass m and the other of mass 3m.

neonofarm [45]

The potential energy that the ball has at the top of the tower is its kinetic energy when it hits the ground. The second ball has more potential energy at the top, because you did more work on it to carry it up there. So it has more KE at the bottom. (A)

3 0

4 years ago

Read 2 more answers

A wire that has a resistance of 1Ω is to be built from an aluminum block of volume 1 cm3

alina1380 [7]

Answer:

L = 5,955 m

Explanation:

For this exercise we must use the relation

R = ρ L / A

where R is the resistance that indicates that it is 1 Ω, the resistivity is taken from the tables ρ = 2.82 10⁻⁸ Ω m, L is the length of the wire and A is the cross section.

As it indicates to us in volume of aluminum to use we divide the two terms by the length

R / L = ρ L / (A L)

the volume of a body is its area times its length, therefore

R / L = ρ L / V

R = ρ L² / V

we clear the length of the wire

L = √ R V /ρ

we reduce the volume to SI units

v = 1 cm³ (1m / 10² cm)³ = 1 10⁻⁶ m

let's calculate

L = √ (1 1 10⁻⁶ / 2.82 10⁻⁸)

L = √ (0.3546 10²)

L = 5,955 m

5 0

3 years ago