# Search results

• Users: Delta
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1. ### Elevator Weight and Acceleration

The 968N comes from a combination of gravitational acceleration and the acceleration of the elevator.
2. ### Projectile Velocity

Not quite. Remember the relationship between velocity, time and distance?

4. ### Force And Energy

Looks good to me, but don't forget the units, and you need to note the direction of the force as well as the magnitude.
5. ### Projectile Velocity

Not yet, you've so far got the horizontal velocity (30.02). We're on to finding the time it takes to travel 20.0m (horizontally). Then we can start on the vertical components.
6. ### Frictionless roller coaster

Energy is always conserved, so if there PE=0 at the bottom of the run, what is the KE? Have another a look at your 5th and 6th answers for a clue.
7. ### Elevator Weight and Acceleration

It's because the question is asking for his weight not his mass. If you can work out his "mass", your can work out his weight.
8. ### Engineering Simple DC Circuit

Try sketching down the outputs you want in order, starting with -5V, 0V (ground), 5V and 10V. How many gaps are there between the nodes?
9. ### Is it wrong to eat a sandwich in front of a starving person?

Maybe the situation has arose from them not liking the sandwich I am eating in front of them.
10. ### Effective resistance between A and B

Try moving the left resistor above the middle resistor, and the right resistor at the bottom. Keep the wires connected as they are, and see what the circuit looks like.
11. ### HIGH o/p dual power amplifier ( HELP )

Bit of a find this, might get one myself. The left and right channels go to pins 11 and 12 as you say. The third will connect to the grounds on 10 and 13. Don't need to worry about current if you're staying within the voltages limits. Just connect straight to it. But also add a cap to...
12. ### Effective resistance between A and B

I was thinking star-delta transformations, but I've just moved them around again and the circuit is simpler than I though ... doh! Where do you get 5R from?
13. ### Effective resistance between A and B

Are you familar with transformations with resistor/impedance networks? This looks to be be one of those. I recommend drawing the circuit another way.
14. ### Choosing Resistor for LED Circuits

For typical LED's, it would be impractical to create a supply just enough to power the LED, remembering an LED is a discrete device. You would be hovering around a critical area of the LED's characteristic curve. There will already be variations in the LED's performance due to manufactruing...
15. ### Choosing Resistor for LED Circuits

Are you connecting more than one LED? If not you just take the LED voltage from the supply voltage and divide it by what current you want to use. Say, for example, you want to power a 1.5V LED at 30mA from a 9V supply. The resistor value would be (9V - 1.5V) / 30mA = 250ohms. The power...
16. ### MIl-PRF-13830 and Inspection of Mirrors

Hi folks. Not expecting much of a response (specialist area) but I'll try. Does anyone know how to inspect mirrors for cosmetic defects?? The HMD project I'm working involves CRT driven combiners, and from that I've become well acquainted with MIL-PRF-13830 on display eyepieces. A...
17. ### Height of a projectile at a certain point

The key to projectile questions are knowing which formula to use, and 9 times out of ten, you need to work out the horizontal components before you can start on the veritical (due to the effect of acceleration on vertical velocity over time). As we have estbalished however, the is a link...
18. ### Very irritating pop-up

Looks like spybot has done the trick, ta very much for that. Some of the things it found i read a little about and looked in the registry myself and they look like what was causing the grief. thanx again.
19. ### Very irritating pop-up

ok, I've been on the internet for some time now and have got used to locating and removing crap from the net that's got itself on to my PC. I now have Norton, Zonealarm, ewido and ad-aware, and i always have to keep going into the system folders, checking installed programs, looking at the...
20. ### Imaginary i

or even \sqrt{(-1-x)(3+x)} :wink:
21. ### EMF - need help - physics

How much do you know about electric and magnetic fields? I would start with V=Blv, but unless that's known as a standard formula, you'd need to go back a few steps.
22. ### News London Shooting: What would you have do?

What facts? I think you're being clung to conspiracy theories. That the marksmen in question was some bent trigger happy copper, protected by corrupt authorities. I agree with the results of the poll, that if I was in their shoes with the limited information I would of had, the events of...
23. ### News London Shooting: What would you have do?

Facts found out about De Menzes after the event are irrelevant. All the man behind the gun knew was the risk to 100's of passengers, and it wasn't just based on colour but every unfortunate, almost freak, circumstance preceding that. I can't emphasize this enough but you are entitled to your...
24. ### News London Shooting: What would you have do?

How many times! None of this was known at the time.
25. ### News London Shooting: What would you have do?

He ran from armed police towards a train full of passengers having just left a building under surevliance in a jacket that didn't suit the weather conditions. Again evidence can only be sought after the event. Any sources? I understand this is in the protocol to shoot five times as one...
26. ### News London Shooting: What would you have do?

That wasn't known until it was too late. And as this poll seems to be showing most people would have shot in that situation, despite the police in general being dubbed trigger-happy boys. A fatal build-up circumstances on the part of the victim and their actions? Police incompetence in...
27. ### News London Shooting: What would you have do?

I think spin network put made some good points, it was a tragic set of circumstances. And I think its also becoming clear how this debate can go into many areas. My opinions were largely based on the actions of the officer in question and the shoot-to-kill policy, and this poll was created...
28. ### News London Shooting: What would you have do?

The team (a) / team (b) thing is news to me, any sources? I guess we can safely assume that if there was a second marksmen team, that they would have been more inclinded towards a shoot to kill decision if given biased information. i.e. he's a terrorist suspect. For the purpose of the poll...
29. ### News London Shooting: What would you have do?

I hoped to try and make it as unbiased as possible. I agree that at the time of making the choice we didn't know what we know now. But with my opinion that he did what he could only do, I wanted to give a devils advocate view to each circumstance, and negate each event that supported a shoot...
30. ### News London Shooting: What would you have do?

London Shooting: What would you have done? A man was pursued by police, suspected of being a suicide bomber and shot dead. The man came from a residence under surveillance, but maybe had nothing to do with it. He wore a largish coat, unusual? or is this irrelevant?, he ran (was it from the...
31. ### News The Ultimate Loss of Civil Liberties: Innocent Man Shot Dead in UK

Ok, I feel a poll coming on here.
32. ### News The Ultimate Loss of Civil Liberties: Innocent Man Shot Dead in UK

We seem to be getting mixed reports over when he started running and if the police actually did give warning. A classic case of chinese whispers I think. All I know is I wouldn't trust the news reports of other countries ( e.g. sky news or CNN). And of the news reports of the UK I would put...
33. ### News The Ultimate Loss of Civil Liberties: Innocent Man Shot Dead in UK

I take it from the suttleties in your story, you believe the officer was at fault. Consider the circumstances: 8 explosions happening all over london killing 56 so far, luckily the last four were unsuccessful. The terrorists of the last four still at large. The residence that the man...
34. ### Medical Asperger's Syndrome

I agree. I'm no expert, but after having autistic kids being pointed out to me, whether its aspergers or at the other end of the ASD scale, you begin to understand there is something different going on. One of the main things being that they seem to be in a world of their own. Just by...
35. ### Braking and Clutch Pedal

I was always taught that you do only press on the brake, but as the engine slows down you begin to push the clutch in. I can't remember what I do now as its subconscious. The only reasons I can think of holding the clutch out is so that the wheel does not lock at first touch, and also (as...
36. ### What is flux?

One thing not to be confused with is that Flux is not a couple of dotted lines that you see in the pics around magnets. But Flux actually surrounds the whole thing, the field lines are just a guide to show what direction the flux is going and what it generally looks like. The best way I can...
37. ### PF Member Photo Thread Archive

Neat idea for a thread. I think its maybe now my turn.
38. ### Stupid experiments you have done

I wanted to test if the neutral line from a power supply was safe to touch based on the fact that the voltmeter only gives out 5V. I took out my desk lamp from its socket and touched the metal instead only to jump 4ft and give meself an electric shock. I'm not sure whether I touched the...
39. ### The Disaster Syndrome

Love that Dilbert, it speaks truth of where I work amongst other places. The comparisons are uncanny.
40. ### The Disaster Syndrome

You mention a device so that you can't do above 65 MPH. Most new cars have at least a rev limiter. You also imply car companies have no inspiration for safety. On the contary cars go through rigirous safety tests that are tightening by the day. For example airbags, ABS, power steering...
41. ### Terrorist Attack hits London, City on Alert

I thought the events of today were sickening enough until I read the comments from bicycle. How thoughtless, surely he can't be allowed to remain on these forums with such senseless voicing against the victims and their families and friends. I agree that this has nothing to do with the...
42. ### 8 bit switch? does it exist?

I can only recommend you continue searching for an 16-8 mux supplier. Failing that you're left with getting a couple of buffer chips. One for the LCD and one for RAM, both connecting to the data bus from the microcontroller. The 8th bit would enable either one buffer or the other.
43. ### 8 bit switch? does it exist?

Most IC's come with enable pins. Why not just connect the lines up to both devices and use the 8th bit as an address line? What LCD and RAM are you using? What's the function of the circuit? What other devices have spare cells in them?
44. ### File-sharing's moral status?

Then again it can be a good thing. Most highly commercial groups make money through tours, royalties and merchandise. For those little known groups file sharing can be a good thing. Would we of seen David Bernal does his thing in the Golf GTI ad and a few movies if it weren't for the...
45. ### Umm Any Ideas?

I'd see a solicitor myself. Or failing that browse around the net for advice, I'm sure there's some online (uk) lawyers and laywer forums out there somewhere, to tell you what your rights are. I believe tenants have a duties document, but in any case this must be breaching health and safety...
46. ### Understanding the good effiency

I would say efficiency is quite simply the ratio of useful "stuff" over the total amount " stuff" available. For example a light bulb has x amount of energy (electrical) available. It uses y amount of energy to produce light, therefore the efficiency is x/y x 100%. Good efficiency is...