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3 years ago

Please Someone Help me I Need Help ASAP PLEASE

Physics

1 answer:

dimaraw [331]3 years ago

4 0

The match making one is Radiation is i think B and Convection i think is C and Conduction i think is A. I think 1 is radiation. Because radiation is transferred between objects or an empty space. Number 2 i think is conduction Because conduction is the transfer of thermal energy between to objects touching. Number 3 i also i think is radiation because radiation transfers between objects. Number 4 i also think is conduction because the spoon was touching a hot pot that was on the stove so then the thermal energy was transferred between the two objects touching. number 5 I think is convection because convection is the transfer of energy by the movement of a fluid, such as air or water. Number 6 i think is radiation because the snake is not touching the lamp and radiation goes all across spaces. Number 7 i think is convection because convection is the movement of a fluid, such as air or water. Hope this helps sorry its so long :)

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You have a grindstone (a disk) that is 95.2 kg, has a 0.399 m radius, and is turning at 93 rpm, and you press a steel axe agains

olya-2409 [2.1K]

Answer:

angular acceleration is -0.2063 rad/s²

Explanation:

Given data

mass m = 95.2 kg

radius r = 0.399 m

turning ω = 93 rpm

radial force N = 19.6 N

kinetic coefficient of friction μ = 0.2

to find out

angular acceleration

solution

we know frictional force that is = radial force × kinetic coefficient of friction

frictional force = 19.6 × 0.2

frictional force = 3.92 N

and

we know moment of inertia that is

γ = I ×α = frictional force × r

γ = 1/2 mr²α

α = -2f /mr

α = -2(3.92) /95.2 (0.399)

α = - 7.84 / 37.9848 = -0.2063

so angular acceleration is -0.2063 rad/s²

3 0

3 years ago

Water flows through a cast steel pipe (k = 50 W m.K, ε = 0.8) with an outer diameter of 104mm and 2 mm wall thickness. Calculate

masha68 [24]

Answer:

The heat loss per unit length is $\frac{Q}{L} = 2981 W/m$

Explanation:

From the question we are told that

The outer diameter of the pipe is $d = 104mm = \frac{104}{1000} = 0.104 m$

The thickness is $D = 2mm = \frac{2}{1000} = 0.002m$

The temperature of water is $T = 90^oC = 90 + 273 = 363K$

The outside air temperature is $T_a = -10^oC = -10 +273 = 263K$

The water side heat transfer coefficient is $z_1 = 300 W/ m^2 \cdot K$

The heat transfer coefficient is $z_2 = 20 W/m^2 \cdot K$

The heat lost per unit length is mathematically represented as

$\frac{Q}{L} = \frac{2 \pi (T - Ta)}{ \frac{ln [\frac{d}{D} ]}{z_1} + \frac{ln [\frac{d}{D} ]}{z_2}}$

Substituting values

$\frac{Q}{L} = \frac{2 * 3.142 (363 - 263)}{ \frac{ln [\frac{0.104}{0.002} ]}{300} + \frac{ln [\frac{0.104}{0.002} ]}{20}}$

$\frac{Q}{L} = \frac{628}{0.2107}$

$\frac{Q}{L} = 2981 W/m$

6 0

3 years ago

Give examples of not useful high friction

Tatiana [17]

Friction can be bad by being too strong or too weak.

Sometimes, when it is too strong, it decreases efficiency since some energy is wasted and turns to heat. Friction can also damage equipment/objects like when you slide it on the floor.

When friction is too weak, like for instance when there is black ice- our center of gravity is displaced too quickly and we can fall. Likewise, if there is a lot of slush on the ground, cars can slip and slide.

6 0

3 years ago

A jeweler is determining the optical properties of an unknown blue gemstone. She uses an angle of incidence of 62°, and measures

Juliette [100K]

Answer:

n = 1.76

Explanation:

According to the rule of ( n1 sin theta1 = n2 sin theta2 )

we know both angles so we insert them to the law and apply n1 = 1

so 1/2 = n2 sin 62 and we get the final answer

3 0

3 years ago