Automatic sliding doors The first automatic sliding doors were described by Hero of Alexandria almost 2000 years ago. The doors were moved by hanging containers that were filled with water. Modern sliding doors open or close automatically. They are equiped with sensors that detect the proximity of a person and an electromic circuit that processes the signals from the sensors and drives the electomotor-based system that moves the doors. The sensors typically emit pulses of infrared light or ultrasound and detect the reflected pulses. By measuring the delay between emitted and received pulses, the system can determine the distance to the object from which the pulse was reflected. The whole system must be carefully designed to ensure safe and accurate functioning. Designers of such doors take into account several variables such as typical walking speeds of people and their dimensions. Let’s try to learn more about automatic sliding doors by analyzing the motion of a single-side automatic sliding door when a person is walking through the door. Figure 2.30 shows the position-versus-time graph of the motion of the edge of the door (marked with a red cross in the photo) from the moment the door starts opening to when the door is closed while a person walks toward and through the door. The doors are adjusted to start opening when a person is 2.0 m away. How long does it take for the door to fully open? a. 1.5 s b. 3 s c. 5.5 s d. 11 s
Automatic sliding doors The first automatic sliding doors were described by Hero of Alexandria almost 2000 years ago. The doors were moved by hanging containers that were filled with water. Modern sliding doors open or close automatically. They are equiped with sensors that detect the proximity of a person and an electromic circuit that processes the signals from the sensors and drives the electomotor-based system that moves the doors. The sensors typically emit pulses of infrared light or ultrasound and detect the reflected pulses. By measuring the delay between emitted and received pulses, the system can determine the distance to the object from which the pulse was reflected. The whole system must be carefully designed to ensure safe and accurate functioning. Designers of such doors take into account several variables such as typical walking speeds of people and their dimensions. Let’s try to learn more about automatic sliding doors by analyzing the motion of a single-side automatic sliding door when a person is walking through the door. Figure 2.30 shows the position-versus-time graph of the motion of the edge of the door (marked with a red cross in the photo) from the moment the door starts opening to when the door is closed while a person walks toward and through the door. The doors are adjusted to start opening when a person is 2.0 m away. How long does it take for the door to fully open? a. 1.5 s b. 3 s c. 5.5 s d. 11 s
Automatic sliding doors The first automatic sliding doors were described by Hero of Alexandria almost 2000 years ago. The doors were moved by hanging containers that were filled with water. Modern sliding doors open or close automatically. They are equiped with sensors that detect the proximity of a person and an electromic circuit that processes the signals from the sensors and drives the electomotor-based system that moves the doors. The sensors typically emit pulses of infrared light or ultrasound and detect the reflected pulses. By measuring the delay between emitted and received pulses, the system can determine the distance to the object from which the pulse was reflected. The whole system must be carefully designed to ensure safe and accurate functioning. Designers of such doors take into account several variables such as typical walking speeds of people and their dimensions.
Let’s try to learn more about automatic sliding doors by analyzing the motion of a single-side automatic sliding door when a person is walking through the door. Figure 2.30 shows the position-versus-time graph of the motion of the edge of the door (marked with a red cross in the photo) from the moment the door starts opening to when the door is closed while a person walks toward and through the door. The doors are adjusted to start opening when a person is 2.0 m away.
Two complex values are z1=8 + 8i, z2=15 + 7 i. z1∗ and z2∗ are the complex conjugate values.
Any complex value can be expessed in the form of a+bi=reiθ. Find r and θ for (z1-z∗2)/z1+z2∗. Find r and θ for (z1−z2∗)z1z2∗ Please show all steps
An electromagnetic wave is traveling through vacuum in the positive x direction. Its electric field vector is given by E=E0sin(kx−ωt)j^,where j^ is the unit vector in the y direction. If B0 is the amplitude of the magnetic field vector, find the complete expression for the magnetic field vector B→ of the wave.
What is the Poynting vector S(x,t), that is, the power per unit area associated with the electromagnetic wave described in the problem introduction?
Give your answer in terms of some or all of the variables E0, B0, k, x, ω, t, and μ0. Specify the direction of the Poynting vector using the unit vectors i^, j^, and k^ as appropriate. Please explain all steps
Another worker is performing a task with an RWL of only 9 kg and is lifting 18 kg, giving him an LI of 2.0 (high risk).
Questions:What is the primary issue according to NIOSH?Name two factors of the RWL that could be improved to reduce risk.If the horizontal distance is reduced from 50 cm to 30 cm, how does the HM change and what effect would it have?
Chapter 2 Solutions
College Physics: Explore And Apply, Volume 2 (2nd Edition)
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