1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Olegator [25]
3 years ago
14

Suppose a person (height of 1.8 m) walks in a room installed with a pyroelectric infrared (PIR) motion detector. The distance be

tween the person and the PIR detector is 5 m. The PIR detector sensor is 3 cm x 1 cm in size.
Estimate the radiated power at the surface of the sensor from the person. Assume that emissivity of human skin/fabric and sensor cap is 0.9. Assume that the person’s body temperature is 37°C and the temperature at the surface of PIR detector is at 18°C. Also assume that there is no radiated power loss through air and Fresnel lens. You can roughly estimate surface area of the person.
Engineering
1 answer:
3241004551 [841]3 years ago
8 0

Answer: b is your best option

Explanation:

You might be interested in
A 20.0 µF capacitor is charged to a potential difference of 800 V. The terminals of the charged capacitor are then connected to
Sergeu [11.5K]

Answer:

a) Q_initial = 16 * 10^-3 C

b) V_1 = V_2 =  (16/3) * 10^2 V

c)  E = 64/15 J

d)  dE = 32/15 J of decrease

Explanation:

Given:

- Capacitor 1, C_1 = 20.0 uF

- Capacitor 2, C_2 = 10.0 uF

- Charged with P.d V = 800 V

Find:

a) the original charge of the system,

(b) the final potential difference across each capacitor

(c) the final energy of the system

(d) the decrease in energy when the capacitors are connected.

Solution:

a)

- The initial charge in the circuit is the one carried by the first charged capacitor.

                           Q_initial = C_1*V

                           Q_initial = 20*10^-6 * 800

                           Q_initial = 16 * 10^-3 C

b)

- After charging the other capacitor, we know that the total charge is conserved among two capacitor:

                          Q_initial = Q_1 + Q_2

- We also know that potential difference across two capacitor is also same.

                          V_1 = V_2 = Q_1 / C_1 = Q_2 / C_2

- Using the two equations and solve for charge Q_2:

                          Q_2 = Q_1*C_2/C_1

                          Q_2 = Q_1*10/20 = 0.5*Q_1

- using conservation of charge:

                          Q_initial = 1.5*Q_1

                          Q_1 = 16*10^-3 / 1.5 = 10.67*10^-3 C

- Hence the Voltage across each capacitor is:

                          V_2 = V_1 = Q_1 / C_1  

                                            = 10.67*10^-3 / 20*10^-6

                                            = (16/3) * 10^2 V

c)

- The energy in the system is:

                          E = 0.5*C_eq*V^2

Where, C_eq is the equivalent capacitance of paralle circuit.

                           E = 0.5*(20+10)*10^-6 *((16/3) * 10^2)^2

                          E = 64/15 J

d)

- The decrease in energy of the capacitors is:

                           dE = E_initial - E_final

Where, E_initial is due to charging of the C_1 only:

                          dE = 0.5*10^-6*20*800^2 - (64/15)

                          dE = 32/5 - 64/15 = 32/15 J

5 0
3 years ago
A crankcase heater is often used to prevent refrigerant from mixing with compressor oil during periods of:
stira [4]

Answer:

Low ambient temperature

Explanation:

Hope this helps. If it did, please mark as brianliest so other people see it. Thanks! - Kai

5 0
2 years ago
Read 2 more answers
A(n) is a detailed, structured diagram or drawing.
monitta

Answer:

Schematics

Explanation:

A schematic is a detailed structured diagram or drawing. It employs illustrations to help the viewer understand detailed information on the machine or object being described. Its main aim is not to help the observer know what the object looks like physically. It is rather aimed at helping the viewer know how the machine works. This is achieved by only including key and important details to the drawing.

It is most times used in the blueprint and user guides of machines and gadgets used in the home to help users know how these things work so that they can do little fixings should there be such needs.

6 0
3 years ago
What is the name of the first federation vessel in star trek hint 17?
Nitella [24]

Answer:

The Fesarius

Explanation:

It's the first vessel

7 0
2 years ago
A screw is a simple machine that can be described as an inclined plane wrapped around a cylinder.
Phoenix [80]

Answer:

thanks thanks thanks thanks

Explanation:

7 0
3 years ago
Other questions:
  • 11 Notează, în caiet, trăsăturile personajelor ce se pot
    13·1 answer
  • The SDS for any chemical used at a job site must be available
    6·2 answers
  • The voltage across a device and the current through it are:
    9·2 answers
  • Due at 11:59pm please help
    14·1 answer
  • A car is stopped at an entrance ramp to a freeway; its driver is preparing to merge. At a certain moment while stopped, this dri
    10·1 answer
  • 2. Ang sangay na nagbibigay-kahulugan sa mga batas ng bansane
    8·1 answer
  • Which word from the passage best explains what the web in the passage symbolizes
    10·1 answer
  • In the planning process of the product development life cycle what is it important to inventory
    7·1 answer
  • What is the difference between a series circuit and a parallel circuit?
    11·2 answers
  • 8. If you push a 2000 N weight up a ramp with 400 N of force and you raise the weight 1 meter,
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!