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Rudik [331]
2 years ago
15

160 students sit in an auditorium listening to a physics lecture. Because they are thinking hard, each is using 125 W of metabol

ic power, slightly more than they would use at rest. An air conditioner with a COP of 5.0 is being used to keep the room at a constant temperature.
what minimum power should be used to operate the air conditioner?
Physics
1 answer:
anastassius [24]2 years ago
8 0

Answer:

minimum power should be used to operate the air conditioner is 4000 W

Explanation:

given data

students  n = 160

power p = 125 W

COP = 5.0

to find out

what minimum power should be used

solution

we know the COP formula that is given below

COP = students × power  / minimum power

minimum power = n × p / COP

put all value

minimum power = n × p / COP

minimum power = 160 × 125 / 5

minimum power = 4000 W

minimum power should be used to operate the air conditioner is 4000 W

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stepladder [879]
Impulse equals Change in Momentum
F = average applied force = to be determined
Δt = time during which the force is applied = 0.50 s
m = mass = 1,700 kg
Δp = change in momentum = to be determined
Δv = change in velocity = to be determined
v1 = initial velocity = 50.0 km/h = 50,000 m/h = 13.9 m/s
v2 = final velocity = 0.00 km/h = 0.00 m/s

F∙Δt = Δp
F∙Δt = m∙Δv
F∙Δt = m∙(v2 - v1)

F = m∙(v2 - v1) / Δt
F = 1,700 kg∙(0.00 m/s - 13.9 m/s) / 0.50 s
<span>F = -47,222 N The negative sign means that the force vector is </span>
<span>applied AGAINST the momentum vector of the rhinoceros.</span>
7 0
2 years ago
A ball is fixed to the end of a rod and is swung in a circle at a constant rate. Consider four scenarios with differing values f
Mamont248 [21]

Answer:

Explanation:

the answer is found below

5 0
2 years ago
What are the real life applications of Hooke's Law?
Anarel [89]

Answer:

1) a rubber band

2) the spring of retractable pen

3) a spring loaded toy gun

Explanation:

Hooke's law states that; provided the elastic limit of a material is not exceeded, the force exerted on an elastic material is directly proportional to its extension. This relationship was first captured by Robert Hooke in 1660 when he asserted that 'as the extension, so is the force!'.

Hooke's law generally deals with elastic or stretchable materials. These materials can be deformed, but returned to their original shapes when the deforming force is removed. This deforming force causes an extension in the material which is directly proportional to the deforming force. That is F= Kx where K is the called the force constant, F is the deforming force and x is the magnitude of extension brought about by the force.

Various real life applications of Hooke's law have been listed in the answer. Any material that makes use of a loaded spiral spring or indeed any kind of elastic material obeys Hooke's law.

5 0
2 years ago
What is the mass of an object that weighs 686N on Earth?
Oxana [17]

Answer:

70 kg is the mass of the object

Explanation:

This question can be solved with this simple formula:

Weight force = mass . gravity

686 N = mass . 9.8 m/s²

686 N /  9.8 m/s² = mass → 70 kg

Note → 1N = 1 kg . m / s²

8 0
2 years ago
An airplane weighing 5000 lb is flying at standard sea level with a velocity of 200 mi/h. At this velocity the L/D ratio is a ma
saul85 [17]

Answer:

98.15 lb

Explanation:

weight of plane (W) = 5,000 lb

velocity (v) = 200 m/h =200 x 88/60 = 293.3 ft/s

wing area (A) = 200 ft^{2}

aspect ratio (AR) = 8.5

Oswald efficiency factor (E) = 0.93

density of air (ρ) = 1.225 kg/m^{3} = 0.002377 slugs/ft^{3}

Drag = 0.5 x ρ x v^{2} x A x Cd

we need to get the drag coefficient (Cd) before we can solve for the drag

Drag coefficient (Cd) = induced drag coefficient (Cdi) + drag coefficient at zero lift (Cdo)

where

  • induced drag coefficient (Cdi) = \frac{Cl^{2} }{n.E.AR} (take note that π is shown as n and ρ is shown as p)    

        where lift coefficient (Cl)= \frac{2W}{pAv^{2} }=\frac{2x5000}{0.002377x200x293.3^{2} } = 0.245

        therefore

       induced drag coefficient (Cdi) = \frac{Cl^{2} }{n.E.AR} = \frac{0.245^{2} }{3.14x0.93x8.5} = 0.0024

  • since the airplane flies at maximum L/D ratio, minimum lift is required and hence induced drag coefficient (Cdi) = drag coefficient at zero lift (Cdo)
  • Cd = 0.0024 + 0.0024 = 0.0048

Now that we have the coefficient of drag (Cd) we can substitute it into the formula for drag.        

 Drag = 0.5 x ρ x v^{2} x A x Cd

Drag = 0.5 x 0.002377 x (293.3 x 293.3) x 200 x 0.0048 = 98.15 lb

8 0
2 years ago
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