What is Rpm: Definition and 248 Discussions

Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is the number of turns in one minute. It is a unit of rotational speed or the frequency of rotation around a fixed axis.

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  1. V

    Small Displacement High RPM Engines

    I'm looking into buying an E34 530i with a smaller 3 liter V8 compared the the 540 4.4 liter V8. A lot of people online say buying a 530 is pointless when you can get the same car with more displacement and more power. I think that's ridiculous since displacement is only 1 of many ways to make...
  2. A

    Low RPM autosuficient system project calculations

    I have a cart which is moved by a wench. One of the wheels will have an alternator used for wind applications at 1032 RPM (after multiplier). At 1032 RPM the alternator produces 13A 90V. I also have a 1:5 multiplier installed. I am thinking of buying two VMAX SLR175 Solar Battery with 175 AH, in...
  3. A

    Low RPM alternator to charge 12V battery

    Hi guys, I am working on a school project. I have an inclined cart mounted on rails moved by a winch. I would like to install an alternator on one of the cart axis, so I can charge a 12V car battery - 20Ah. The wheel turns at 12 RPM. At that speed the alternator will not work, so I am also...
  4. N

    Stepper motor increase rpm but keep torque

    Is it possible that I keep the typical working torque but increase the rpm by raising my voltage to my motor? I have this motor and control board: http://uk.rs-online.com/web/p/stepper-motors/3514631/ http://uk.rs-online.com/web/p/stepper-drives-indexers/2407920/?origin=PSF_421243|acc...
  5. S

    Automotive How do the accelerator pedal and rpm interact in an internal combustion engine?

    Hello everyone, this is my first contribution in this forum, I'm aware that this question had been asked many times either in this forum or elsewhere and I have indeed read at least one thread with a similar topic, however, unfortunately, I have yet to find specific answers that nail the core...
  6. S

    High rpm quiet bearings needed

    Hello, we have been using high precision angular contact ball bearings to support a shaft with diameter of 1". At some 25,000 rpm, the noise reaches 120 dB. What other mechanical bearings would be a better choice. The current ones are quite loud. Thanks.
  7. C

    Installing sensors to monitor current and rpm

    I would like some assistance to select the right sensor/transducer to monitor current from an inverter to the spindle motor it feeds. If it is possible to get RPM signals from the inverter please advice on how to go about it. Please suggest the most suitable sensor/s to achieve both current and...
  8. A

    How to Calculate RPM of Wind Turbine generator

    I am going to design 10 kw, Permanent Magnet, Direct Drive Wind Turbine Generator. The main problem is, how to determine the rotational speed of the Wind Turbine. This is important for me because I have to design the PMG and its rated rpm values...
  9. S

    Relation between SFC vs RPM in diesel engine?

    What is the relation between sfc vs rpm in diesel engine and why does it happen like that ? what is relation between air flow vs rpm ??
  10. bsmithysmith

    MHB Finding a radius when an angular speed in RPM is given

    When being burned in a writable CD-R Drive, the angular speed is often faster when playing audio... When writing along the outer edge, the angular speed of one drive is about 4800 RPM (Revolutions per minute). Find the linear speed. The question above it, or before this one was with CD's radius...
  11. S

    Clarifying Torque, RPM, and Radius in Motor Dynamics

    Presently, three things I need clarity on, please. Thing 1: I'll be using the following equation to arrive at fair approximations of torque and rpm, given various motor rotors of different radii, masses, and with different stator coils (electromagnets) providing the repelling force... T = I x...
  12. J

    RPM required to simulate Earth's gravity (Centrifugal acceleration)

    Homework Statement Here's the problem: "On a journey to Mars, one design is to have a section of the spacecraft rotate to simulate gravity. If the radius of this section is 30 meters, how many RPMs must it rotate to simulate one Earth gravity (1 g = 9.8 meters/sec^2)?" Homework...
  13. S

    Bearings for 200,000 rpm and up

    Hello, we are interested in high-speed bearings -- 200,000 rpm and up bearing size: inner diameter: 0.5cm - 1cm outer diameter: up to 3cm thickness: up to 1cm Many sites offer high-speed dental bearings, but they are quite small in size... Would anyone have an idea about a...
  14. S

    What is the most cost-effective way to generate electricity from a waterwheel?

    Hi all, new to the forum and hoping I might get some ideas for a project I am working on, not an Engineer or very well technically educated, so please go easy on me :smile:. What I wish to do is to build a waterwheel which will supply electrical power to my home. I have been doing some...
  15. Psinter

    Vehicle's RPM do not match speed. Why?

    I've been observing cars RPM and noticed that automatic transmission American cars reach 60 mph at 2250 RPM while automatic transmission Japanese cars reach 60mph at 2500RPM. Why is that? Like, what determines RPMs? The rotation from what is being measured?
  16. J

    Circular motion question - finding rpm

    Homework Statement A 0.60 kg sphere rotates around a vertical shaft supported by two strings, as shown. If the tension in the upper string is 18 N. Calculate the tension in the lower string? the rotation rate (in rev/min) of the system? Homework Equations v=2(pi)r/T Fr= mv^2/r ω =...
  17. D

    Frequency versus motor RPM and number of poles

    Which equation is correct I have seen both- F=N/60*P Or F=N/120*P This is Frequency, N=RPM P=Poles
  18. A

    How can I convert force (N) to RPM for my plant uprooting device?

    Hi, I have a question hope you can help me with. I am working on measuring plant uprooting force by using a denamometer. I want to convert this force (10 N) to RPM to apply this on my uprooting device. Thanks!
  19. M

    RPM Problem with Duke's Single-Cylinder Engine

    I am facing this RPM problem with my single-cylinder engine(Duke's) that I have used in my project.. Even though the ECU is programmed to allow RPM upto 12,000 revs but still engine can only reach 6,000 when the clutch is engaged...it can go near to 12,000 only while the clutch is disengaged...
  20. P

    Is it okay to increase DC motor RPM by using higher voltage

    Hello guys I'm looking for a motor for my arrow saw project. I would like to use it to cut carbon arrows. Found one motor in the shop that is pretty small and will work perfectly with my jig. But it's rpm's are only 1650 and I need at least 8000 RPM. Is it possible to increase the motor RPM's...
  21. A

    Increase RPM by decreasing stroke?

    To begin I'll just give a summary of what I'm looking to do, and then explain further for those who are looking for more information. The goal of the engine is having a forced induction motor capable of revving to higher RPMs (more power at the higher RPMs with FI) while still being somewhat...
  22. T

    What is the RPM of an erector set motor with 4 AA batteries?

    This is a really dumb question that I have not found an answer for. I recently bought an erector set with a 3-6 volt motor. It has the option of 2 or 4 AA batteries. I am trying to figure out what the RPM's are with 4 AA batteries for a small hobby project of mine. I know this is simple...
  23. D

    Hp vs rpm to displacement vs time graph?

    Hello, I am a high school student trying to compare two motorcycles on a displacement vs time graph. The information I have is the mass of riders, mass of bikes, gear ratios, tyre circumference and dyno results indicating hp vs rpm. I am not taking air/rolling resistance into consideration...
  24. M

    Finding energy from Inertia and RPM

    Hello, I'm working on a generalized model for motor / gear systems in SPICE and came across something I don't understand: Given that the inertia, J, is in kg m^2 and my base unit for angular velocity, w, is kRPM and the basic equation for energy is E = 1/2 J * w^2 How or what is the...
  25. siddharth23

    Calculations for LMP for certain RPM of hydraulic motor

    If I want the output of a hydraulic motor to be of a specific RPM, then knowing the pressure of the oil in the circuit, how does one calculate the LPM of the pump corresponding to that RPM?
  26. Z

    Turbofan Spool RPM: Mathematical Relation for Performance

    Hello, I am looking for a mathematical relation describing spool RPM and performance (any parameter) of turbofan engine. Kindly help. Thanks. Regards, Z
  27. O

    How Do Torque and RPM Relate to Lifting Weights in Mechanical Systems?

    Just wondering if someone can help explain how to go about figuring out this paper. Thanks!
  28. I

    How to raise RPM of 3ph inductive motor

    As the title says, I need to raise the RPM of a 3ph 480VAC motor by approximately 20%. I looked into Variable speed drives but from what I have seen, they are used to drive the motor from 20-100% of input voltage. Any ideas on what to look for? For reference, motor power is 3HP. Thank...
  29. B

    Help Calculating RPM of a rotatory atomizer thats powered by pneumatic

    Hello everyone, I am a recent horticulture graduate and as such, I take a long time figuring out physics problems.:confused: I hope I could trouble you guys for a possible solution to my problem. I am making an rotary atomizer that is pneumatically powered and need to find out how fast i...
  30. C

    What is the relationship between generator output and RPM?

    First of all, if you have a generator with an open circuit, and you are pedal powering it, where does the energy go? I would say it is lost as heat, but not sure what could heat up. The coils in the generator itself? Next, what happens if you short the output of a generator? Does it make it...
  31. N

    How to calculate RPM on paper?

    I am trying to design an electric motor and calculating how much electrical power it consumes is easy. Trying to figure out the horsepower it produces on paper is not. I can calculate the torque of the motor, but in order to calculate horsepower I need the RPM. Does anyone know how I can figure...
  32. S

    Embeeded RPM sensor calculation programming assistance

    Hi i am doing a side project of displaying RPM speed on the Altera development board DE0 which i have running at 10MHZ. i have got a digital input from a hall effect sensor that has a frequency range from 1.6 to 166.6 Hz. the signal incoming has a duty cycle of 50% to calculate the...
  33. S

    How much energy could I create with a given amount of rpm?

    I'm doing a personal project and need some help on things I could not find just on the Internet. If I have a device that can produce 65 rpm with 70 lbs of force on each revolution, and the drive shaft was connected to a generator...(here come the questions, and I know that the numbers...
  34. I

    How Can We Find the RPM of a CD Through Audio Analysis?

    In this video, a CD accelerates until it breaks: Here is one comment: The flaw that he made is that he assumed that there is one CD revolution per cycle in the sound wave, right?
  35. C

    Calculating Wind Turbine RPM from Generator Voltage Fluctuations

    Hello, I am trying to build a SIMULINK model in Matlab in order to determine the RPM of a wind turbine. Can someone please tell me how I can obtain the RPM of a wind turbine from the voltage fluctuations of a generator? Any good sites in the subject are also welcome. Thanks in advance.
  36. C

    Electric motors and gears: torque, rpm questions

    Hi guys, new here to the forum. I was an electrical engineering student but am now working on more of a mechanical issue so I'm a bit out of my element. I am working with a small electric motor attached to a gearbox. The final gear opens and closes a metal valve. I am having trouble finding...
  37. 0

    How Can A High-Torque Motor Have Low a low RPM

    Torque is the rotational force. If there is more force, how can the motor be slow? I'm building a DC motor and read that given a constant amount of coil, creating a very dense coil will increase torque but lower RPMs. Conversely, making it looser (bigger radius) increases RPM but lowers torque.
  38. M

    Automotive Troubleshooting Low RPM Oil Flow in Diesel Engines

    A diesel engine when cranks 300 rpm find no flow of oil ? what will be reason
  39. P

    Circular Motion - RPM and Radius question

    Homework Statement A manufacturer of CD-ROM drives claims that the player can spin the disc as frequently as 1200 revolutions per minute. a. If spinning at this rate, what is the speed of the outer row of data on the disc; this row is located 5.6 cm from the center of the disc? b. What is the...
  40. M

    Calculate RPM From Pendulum Swing Set

    Pendulum into RPM?? Hi I'm trying to throw together a concept design for a swing set which can convert kinetic energy into mechanical energy. In short I would like a swing set, using one way roller bearings to drive an output shaft but am unsure where to start. If I have a mass (m)...
  41. S

    Sumobot Competition: Torque vs RPM?

    hi .. ... i am entering a sumobot competition..weight limitation 1kg..dimensions 150mm*150mm...what is more important torque or rpm...say i have 10 rpm motors with 38kg torque ...and ..60 rpm motors with 20 kg torque...which should i go for...due to the size limitation ..i can go only for 2...
  42. W

    Calculate rpm with circular motion

    Homework Statement Imagine that NASA plans to builds a large donut-shaped space station. The station will rotate in outer space in order to simulate gravity. If the station has a radius of 200m, what must be its rotation speed in revolutions per minute, to produce an artificial gravity of 0.8...
  43. I

    Is there a relationship between gear RPM and number of teeth?

    Hi guys, I was doing my tutorial and given the angular velocity of the first gear, we were required to calculate the angular velocity of the 8th gear given just the no. of teeth for all the gears. Now I know that there must be a faster way of calculating the angular velocity of the 8th...
  44. T

    Self-lubricating thrust washers and 4500 rpm shaft shaft

    I hope you all will permit a question from a non-scientist seeking some practical guidance on a vintage table saw restoration. I have a 1930s era table saw whose 5/8" shaft spins at 4500 rpm inside a porous bronze bearing that is lubricated with SAE 20 oil. On the motor pulley side of the...
  45. T

    Looking to calculate horsepower by mearuring the change in rpm

    as the title states I am looking to solve how to calculate power (horsepower) by measuring the change in rpm over a few seconds. torque will be kept constant at 200lbs/ft. hp= (torque x rpm) / 5252 since torque will be held constant it reduces to: hp= C x rpm where C is 200/5252 so...
  46. S

    Solving RPM Problems: Understanding Maximum Speed and Revolutions

    Homework Statement Q1) If 4,180rpm is 38% of the max rpm speed what is the max rpm speed? Q2)Determine the number of revolutions a gear completes in 30 seconds when the gear turns at 100 revolutions per min 2. The attempt at a solution Q1) Alright for this part, I was pretty...
  47. G

    Calculating Centripetal Acceleration of a 7200 RPM Hard Drive

    Homework Statement The hard drives of many desktop computers spin at a maximum rate of 7200 rpm. If the diameter of the spinning disk in the harddrive is 3.51 cm, calculate the magnitude of the centripetal acceleration on the outside radius of the disk. Homework Equations ac=v2/r...
  48. M

    A wheel is making 240 rpm and after 30 sec and after 30 sec

    1 ) A wheel is making 240 rpm and after 30 sec and after 30 sec it is running at 150 rpm . A) Find the time elapse before it stops if the retardation is uniform ? B) Find the time elapse after it stops if the retardation is uniform ? my answer : w0 = 240 rpm = 8Pi rad/s w = 240 rpm =...
  49. C

    RPM vs Torque, I, Mech HP, Eff, and Fp of an Induction Motor

    I need to create graphs of: 3 Phase Torque vs RPM Current vs RPM Mechanical Power (HP) vs RPM Efficiency vs RPM Power Factor vs RPM for Slip between nearly 0 and 1 for a 5HP, 60 hz, 440Vac, 4 pole, 3 phase induction motor. I'm having trouble finding equations online relating...
  50. M

    Why is fuel consumption higher at low RPM?

    Why are usually more wasteful fuel engine at low RPM, as the example image below, 900 RPM more wasteful fuel consumption than 1600 RPM.
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