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3 years ago

Explain how a refrigerator works to cool down warm objects that would otherwise be room temperature

Physics

1 answer:

expeople1 [14]3 years ago

8 0

Answer: evaporation

Explanation:

Refrigerators work by causing the refrigerant circulating inside them to change from a liquid into a gas. This process, called evaporation, cools the surrounding area and produces the desired effect.

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Consider a rifle, which has a mass of 2.44 kg and a bullet which has a mass of 150 grams and is loaded in the firing chamber.Whe

svetlana [45]

Answer:

a. 0 kgm/s

b. 0 kgm/s

c. 66 kgm/s

d. -66 kgm/s

e. 0 kgm/s

f. -27.05 m/s

g. 173.68 N

h. 12.58 m/s

i. 0.772 m

j. 14487 J

Explanation:

150 g = 0.15 kg

a. Before the bullet is fired, both rifle and the bullet has no motion. Therefore, their velocity are 0, and so are their momentum.

b. The combination is also 0 here since the bullet and the rifle have no velocity before firing.

c. After the bullet is fired, the momentum is:

0.15*440 = 66 kgm/s

d. As there's no external force, momentum should be conserved. That means the total momentum of both the bullet and the rifle is 0 after firing. That means the momentum of the rifle is equal and opposite of the bullet, which is -66kgm/s

e. 0 according to law of momentum conservation.

f. Velocity of the rifle is its momentum divided by mass

v = -66 / 2.44 = -27.05 m/s

g. The average force would be the momentum divided by the time

f = -66 / 0.38 = 173.68 N

h. According the momentum conservation the bullet-block system would have the same momentum as before, which is 66kgm/s. As the total mass of the bullet-block is 5.1 + 0.15 = 5.25. The velocity of the combination right after the impact is

66 / 5.25 = 12.58 m/s

i. The normal force and also friction force due to sliding is

$F_f = N\mu = Mg\mu = 5.25*9.81*0.83 = 42.75N$

According to law of energy conservation, the initial kinetic energy will soon be transformed to work done by this friction force along a distance d:

$W = K_e$

$dF_f = 0.5Mv_0^2$

$d = \frac{Mv_0^2}{2F_f} = \frac{5.25*12.58^2}{2*42.75} = 0.772 m$

j.Kinetic energy of the bullet before the impact:

$K_b = 0.5*m_bv_b^2 = 0.5*0.15*440^2 = 14520 J$

Kinetic energy of the block-bullet system after the impact:

$K_e = 0.5Mv_0^2 = 0.5 * 5.25*12.58^2 = 33 J$

So 14520 - 33 = 14487 J was lost during the lodging process.

3 0

3 years ago

Work out the area of a rectangle with base, b=20mm and perimeter, p=50mm

Korvikt [17]

Answer:

100mm²

Explanation:

the other side: (50 - 20 × 2) ÷ 2 = 5

5 × 20 = 100

7 0

3 years ago

Read 2 more answers

You place an object 30.0 cm from a concave mirror of 15.0 cm focal length. The object is 1.8 cm tall. Find the image position an

Softa [21]

Answer:30 cm

Explanation:

Given

object distance $u=30\ cm$

focal length of concave mirror $f=15\ cm$

height of object $h_o=1.8\ cm$

Using mirror formula

$\Rightarrow \frac{1}{v}+\frac{1}{u}=\frac{1}{f}$

$\Rightarrow \frac{1}{v}=\frac{1}{15}-\frac{1}{30}$

$\Rightarrow \frac{1}{v}=\frac{2-1}{30}$

$\Rightarrow v=30\ cm$

and magnification is

$\Rightarrow m=\frac{-v}{u}=\frac{h_i}{h_o}$

$\Rightarrow \frac{-30}{30}=\frac{h_i}{1.8}$

$\Rightarrow h_i=-1.8\ cm$

So height of object is same as of object .

Position :image is formed at the spot where object is placed.

4 0

3 years ago

Which substance—wood or steel—is the better conductor? A conductor is a material that requires very little

bogdanovich [222]

Steel is the correct answer because steel when on being applied heat will either change its state that too after hours because of its melting point being high or remain in that position only whereas wood turns into ashes...that is why we use metal utensils in the kitchen

7 0

4 years ago

A car accelerates uniformly from rest to a speed of 22.4 km/h in 6.1 s. find the distance it travels during this time.

stepladder [879]

You will need to add 22.4+6.1

7 0

3 years ago