a) Summation of forces on the y-axis T1 sin20 T2 sin20 = 190 Summation of forces along the x-axis T1 cos20 = T2 cos20 T1 = T2 a) T1 = 190/(2 sin20) = 277.76 N T2 = 277.76 N ----------these are the tension of the wires. b) If the angle between is reduced to 110 degrees. Then the tension will be, T1 =T2 = 190/( 2 sin 35) = 165.63 N
1. A street lamp weighs 110 N. It is supported by two wires that form an angle of 100Â° with each other. The tensi
Resolving forces vertically . Two angles make 100 degress with each other . make angle of 100/2 = 50 Degress with the vertical Tcos50Tcos50=110 T=85.5 N. b) Now they make an angle 0f 70/2=35 with the vertical Tcos35Tcos35=110 T=67.1 N.
2. A street lamp weighs 150 N. It is supported by two wires that form an angle of 120 degrees with each other..?
Any system...let me repeat...any system that is not accelerating (or decelerating) has balanced forces acting on it so that the net force (f) is exactly zero. This results because f = ma = 0 if and only if a = 0 for a mass m. OK your weight W = 150 N is not accelerating, in fact it is static; so there is no motion whatsoever. So f = 0 = ma for the system, which includes the weight and the two wires. This means that something is canceling out the weight because f = ma = W - F = 0; where F is that "something" canceling the weight (W). The only "something" you've defined for your system is the forces pulling up by the attached wires. Since there are two wires, each one has a share of that upward force. By "upward" we mean vertical force acting in a direction opposite of the weight (W). As there are 120 deg between the two wires, the vertical force for both wires is W cos(60) = Fv and for each individual wire, it's Fv/2 = (W/2) cos(60). Similarly, the horizontal force on each wire is Fh = (W/2) sin(60). Since the vertical and horizontal forces form a right angle for each wire, the force along each wire, the tension, is T = sqrt(Fv^2 Fh^2). And, by substitution, T = sqrt((W/2)^2 cos(60)^2 (W/2)^2 sin(60)^2) = sqrt[(W/2)^2 [sin(60)^2 cos(60)^] = sqrt((W/2)^2) = W/2. a. Thus, the tension (T) in each wire is one half the weight of the street lamp = W/2. b. Following the same line or reasoning used to find the tension at 120 deg, we see that the angle makes no difference because sin(deg)^2 con(deg)^2 = 1.0 no matter what deg is. Tension, therefore, will still be W/2 in each wire with 90 deg between them. The important thing to remember is that, if the system is not accelerating or decelerating, the net force on it is zero. So all the forces acting on it will cancel out.
3. Smart street lamp tech could put speed cameras everywhere
Internet-connected, "smart" streetlamps and intersections are being touted as the next big thing in the world of automotive technology, but while they would arguably be a major benefit to road safety and driver convenience, such systems could also create a blanket of speed cameras. The concept of networked road infrastructure is not new, and in many cities the lights and built-in sensors of most intersections are already monitored remotely. The next step, however, is to add more sensors into the mix to keep tabs on the precise positions of cars and pedestrians, while beaming out that information to any cars in the immediate area. It's a noble idea. Say, for example, that there's a pedestrian about to cross the road in front of you but is obscured by a truck in the next lane (below). Such a system could give you advance warning - or automatically slam on the anchors - before the situation becomes life-threatening. Accidentally running a red light could also become a thing of the past too, as your car would be alerted if it's in danger of crossing a stoplight, while the extra data generated would be critical to making autonomous vehicles function both efficiently, and safely. That safety-critical information would be sent directly to cars in the vicinity through the Direct Short Range Communications protocol, rather than via a cloud server over the internet. With ultra-low transmission times, DSRC is a better choice for that kind of vehicle-to-infrastructure information transfer. The benefits do not stop there. More intelligent vehicle monitoring would allow traffic light sequences to respond to changes in traffic flow, easing congestion and reducing the amount of time wasted by sitting still at intersections. With each junction connected via the internet, slow-moving traffic jams could be cleared far more efficiently by phasing traffic light cycles sympathetically. That said, safety is the main driver behind the smart intersection idea. Continental, which showcased its latest vision for digitally-enhanced street infrastructure at the Continental TechShow earlier this month, says its aim is to use its sensor technology to reduce the number of crashes globally. With 40 percent of road crashes in the United States occurring at intersections, Continental says it makes sense to start its smart infrastructure efforts there. Meanwhile, sensor modules strapped to ordinary lamp posts - Continental's "Intelligent Street Lamp" concept, below - holds the potential to stretch the digitisation of the road network well beyond illuminated intersections. Besides informing nearby intersections of approaching traffic, the street lamp modules would also be able to monitor parking spaces and direct nearby cars to vacant spots. They could even survey air and noise quality, uploading that information to the cloud. If there's a hazard on the road, such as a fallen tree or vehicle accident, they could alert approacing cars via the DSRC protocol. However, even Continental admits that the sensor technology could be adapted to other purposes, such as extending the reach of speed enforcement well beyond main roads. "It depends on the country. I cannot make that general statement, because it's really specific, but every market has its requirement. If you look at how speeding, for example, is solved today by radar technology, this is the technology that we are implementing here in our sensor, so what is possible today can be done in future done by a street lamp-mounted sensor." But that's not to say that Continental's system will automatically fine those creeping above the speed limit wherever it's installed. In fact, data protection laws in Europe mean that kind of surveillance is be expressly forbidden. "Of course, everything we are doing here [in Europe] is GDPR (General Data Protection Regulation) compliant - it's about taking good care of an individual's personal information. We solve that by not transmitting any personal data at all, like a licence plate." There are, however, no such data protection laws in Australia. According to Continental, if the client city or state wants the ability to use its smart streetlights for speed enforcement, it has the technological means to do so. Cost, however, may be the only obstacle to putting that tech on every street. "If you look at more advanced systems like combining camera and radar, which means detecting over-speeding through license plate recognition at the same time and automatically fining those people, that is a use case that today is probably only happening in the Chinese market right now - but we will see how the market develops." In many Chinese cities citizens can be detected by CCTV cameras and identified via facial recognition, with an AI system automatically fining those detected breaking the law by, for example, jaywalking - an extension of that government's mass surveillance program and a precursor to its infamous "social credit" system. "The concept we have here is a modular concept, where a city can really address their specific 'pain points' - which are very individual". "For example, the US is using gunshot recognition on street lamps, so microphones on streetlamps can hear a gunshot, and through triangulation you can know where the gun was fired. At the same time the waveform is analysed and you can know which kind of gun it was." While Australia does not have the same issue with gun crime or the draconian AI-driven 'social credit' system of China, the prospect of putting a speed camera in every street may prove to be an attractive idea to police and councils eager to clamp down further on speeding motorists - while also eventually delivering the safety benefits touted by Continental as cars become increasingly connected.