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3 years ago

10

A cold glass of iced tea warms quickly on a hot day through the process of A. conversion. B. insulation. C. conduction. D. expan

sion.

2 answers:

r-ruslan [8.4K]3 years ago

7 0

C) conduction. let me know if I'm wrong

kvv77 [185]3 years ago

6 0

I think that the answer to your question is C. Conduction

You might be interested in

Describe one way in which entropy can increase when reactants turn into products Answer in a complete sentence

Ann [662]

Answer:

Explanation:

Entropy is the degree of randomness of a system which it can increases as the temperature of the reactants is increased to yield product.

4 0

2 years ago

Four identical particles of mass 0.980 kg each are placed at the vertices of a 4.14 m x 4.14 m square and held there by four mas

Zielflug [23.3K]

Answer:

a) The rotational inertia when it passes through the midpoints of opposite sides and lies in the plane of the square is 16.8 kg m²

b) I = 50.39 kg m²

c) I = 16.8 kg m²

Explanation:

a) Given data:

m = 0.98 kg

a = 4.14 * 4.14

The moment of inertia is:

$I=mr^{2} \\r=\frac{a}{2} \\I=m(a/2)^{2} \\I=\frac{ma^{2} }{4}$

For 4 particles:

$I=4(\frac{ma^{2} }{4} )=ma^{2} =0.98*(4.14)^{2} =16.8kgm^{2}$

b) Distance from top left mass = x = a/2

Distance from bottom left mass = x = a/2

Distance from top right mass = x = √5 (a/2)

The total moment of inertia is:

$I=m(\frac{a}{2} )^{2} +m(\frac{a}{2} )^{2}+m(\frac{\sqrt{5a} }{2} )^{2}+m(\frac{\sqrt{5a} }{2} )^{2}=\frac{12ma^{2} }{4} =3ma^{2} =3*0.98*(4.14)^{2} =50.39kgm^{2}$

c)

$I=2m(\frac{m}{\sqrt{2} } )^{2} =ma^{2} =0.98*(4.14)^{2} =16.8kgm^{2}$

8 0

2 years ago

un motor electric efectueaza un lucru mecanic de 864 j in 0.5 min.tensiunea la bornele sale este de 12v si este parcurs de un cu

GrogVix [38]

Answer:

96%

Explanation:

To find the values of the motor efficiency you use the following formula:

$E=\frac{P_o}{P_i}100$

P_o: output power = 864J/0.5min=864J/30s=28.8W

P_i: input power = I*V = (3A)(12V) = 36W

By replacing this values you obtain:

$E=\frac{28.8W}{30W}*100=96\%$

hence, the motor efficiency is about 96%

traslation:

Pentru a găsi valorile eficienței motorului, utilizați următoarea formulă:

P_o: putere de ieșire = 864J / 0.5min = 864J / 30s = 28.8W

P_i: putere de intrare = I * V = (3A) (12V) = 36W

Înlocuind aceste valori obțineți:

prin urmare, eficiența motorului este de aproximativ 96%

3 0

2 years ago

An airplane of mass 1.60 ✕ 104 kg is moving at 66.0 m/s. The pilot then increases the engine's thrust to 7.70 ✕ 104 N. The resis

Ivan

(a) No, because the mechanical energy is not conserved

Explanation:

The work-energy theorem states that the work done by the engine on the airplane is equal to the gain in kinetic energy of the plane:

$W=\Delta K$ (1)

However, this theorem is only valid if there are no non-conservative forces acting on the plane. However, in this case there is air resistance acting on the plane: this means that the work-energy theorem is no longer valid, because the mechanical energy is not conserved.

Therefore, eq. (1) can be rewritten as

$W=\Delta K + E_{lost}$

which means that the work done by the engine (W) is used partially to increase the kinetic energy of the airplane ( $\Delta K$ ) and part is lost because of the air resistance ( $E_{lost}$ ).

(b) 77.8 m/s

First of all, we need to calculate the net force acting on the plane, which is equal to the difference between the thrust force and the air resistance:

$F=7.70\cdot 10^4 N - 5.00 \cdot 10^4 N=2.70\cdot 10^4 N$

Now we can calculate the acceleration of the plane, by using Newton's second law:

$a=\frac{F}{m}=\frac{2.70\cdot 10^4 N}{1.60\cdot 10^4 kg}=1.69 m/s^2$

where m is the mass of the plane.

Finally, we can calculate the final speed of the plane by using the equation:

$v^2- u^2 = 2aS$

where

$v=?$ is the final velocity

$u=66.0 m/s$ is the initial velocity

$a=1.69 m/s^2$ is the acceleration

$S=5.00 \cdot 10^2 m$ is the distance travelled

Solving for v, we find

$v=\sqrt{u^2+2aS}=\sqrt{(66.0 m/s)^2+2(1.69 m/s^2)(5.00\cdot 10^2 m)}=77.8 m/s$

8 0

2 years ago

What unit is used for speed?<br> 1. m/s<br> 2. S<br> 3. m/s2<br> 4. m

bixtya [17]

Answer:

The unit of speed is m/s.

7 0

2 years ago