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  1. U

    Help to understand Newtons Law

    Homework Statement I am trying to understand a diagram I have of a gymnast hanging from a bar. She weighs 50kg and is not swinging, just hanging. In the diagram it has her weight as 500N (using 10/m/s/s for gravity * 50kg) but the bar she is hanging from has an upward arrow with 550 N next to...
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    How is math education in the US structured ? Pre algebra , calc etc

    I was trying to establish form high school up to the pint where you are about to start university, in what order are the maths classes taught. where I live they are just taught as level 1, 2 and 3. But I left school long before these were introduced so have idea what they refer to.
  3. U

    How is math education in the US structured ? Pre algebra , calc etc

    I wanting to do some papers at university, however I have long been out of high school and never really don math or science at high school. As an adult I am now keen to pursue some math papers and was wondering what kind of background I need. I have looked through various web pages and they...
  4. U

    Learning maths concepts …not just how to do an equation

    I tried posting in the education section but was unable to start a topic… Anyways…I'm trying to reteach myself maths from back in the school days in hope of doing a calculus paper at university. I have realized that a lot of books and materials seem to teach you how so l've equations and...
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    Re-learning math (books?)

    I'm in a similar situation, in that I have gone to learning maths again as an adult and while the odd piece of maths form here and there has stuck with me, I often can just plug in numbers to a formula and get an answer. ..BUT…if you asked me why it worked that way I'd be stumped and possibly...
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    How do derivatives provide answers for optimization problems ?

    I' at a a very very very basic level of calculus and usually have to watch a video or read something basic just to understand the basics. I'm fascinated by optimization equations, for example what is the largest area that can made with 500m of fencing. So at some point in solving this we end...
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    Archived Help with internal moments = external moments

    Homework Statement Internal moments need to equal external moments, work out the total of the internal moments. The object has a mass of 2 kg Homework Equations I have obtained the moment about I (labelled as MI) + Iα The Attempt at a Solution the moment about I (MI)...
  8. U

    How to find forces acting on object on a slope?

    here is my latest diagram I'm now starting to think Soh Cah Toa isn't actually relevant there ? Fn = G cosσ Ft = Gσ I'm unsure where these two formulas/equations have come from and why Soh Cah Toa isn't relevant here... I must be missing something fundamental
  9. U

    How to find forces acting on object on a slope?

    Thanks NascentOxygen. Unfortunately I dont quite get why the answers are what they are. I have drawn myself a new triangle which shows the two vector forces but I still don't understand where the answers have come from. Especially Fn = G cosσ. I thought cos in basic terms meant...
  10. U

    How to find forces acting on object on a slope?

    Homework Statement an object is at rest on a slope at angle of σ Using trigonometry, solve the forces acting at Ft and Fn Homework Equations Soh Cah Toa The Attempt at a Solution sin σ = G/Ft sin σ /Ft = G G/ sin σ = Ft (my final answer) Book says correct answer is Ft = G sinσ...
  11. U

    Torque, rotational inertia and angular acceleartion

    what happens though if the body isn't rotating and I want to start it rotating but can't apply enough force to do so ? I'm still applying torque though ....aren't I ?
  12. U

    Torque, rotational inertia and angular acceleartion

    Homework Statement In order to link these into a logical sequence, how do they fit together Homework Equations I = rotational inertia a = angular acceleration (I know a different symbol is usually used) τ= force x moment arm distance The Attempt at a Solution so....to...
  13. U

    What is Torque and what is correct formula?

    I'm struggling with the concept of torque as I read more I get further confused. I read some sources and they say torque and moments are interchangeable, yet other sources make a specific effort to keep the two separate. So question one is , what is the difference between torque and a moment...
  14. U

    Delta V/ delta t vs. dv/dt

    I know delta means change , but I don't what the difference between Δv/Δt vs dv/dt is ? I am at the noob end of calculus so trying to grasp how to interpret things like dv/dt or what what dv would mean if it were standing alone. TIA
  15. U

    Help understanding class content and keeping up

    This may be the wrong section , but I figure it was education relevant. In class I can't always keep up with the current lecture, but then when it starts incorporating previous lectures and the principles I can find it even harder to keep up. I notice some students can start to piece it...
  16. U

    Position - time graph

    I think that is correct, the slope at that particular point is your velocity.
  17. U

    What does the area under a Distance vs Time graph indicate

    Homework Statement Given a graph with distance (in meters) on the y axis and time (in seconds) on the x axis what does the area under this graph illustrate ? The object has a velocity of 1m/s so after 5 s it has travelled 5m. Homework Equations This is a linear line (i.e y=x) so the area...
  18. U

    Why is W=m*g relevant if I am standing still and not moving ?

    Thanks for the help with this.....much appreciated. Still trying to get my head around the F=m*a is equivalent to W= m*g statement. So this is not true then (in the case where I am standing still on the footpath) If I am not accelerating to the center of the earth due to the force of the...
  19. U

    Why is W=m*g relevant if I am standing still and not moving ?

    Homework Statement Why is gravity still 9.81m/s/s when we are standing still ? and why do I have a weight when I am standing still ? Homework Equations F=m*a W=m * g a= (final velocity - initial velocity)/ time The Attempt at a Solution So it requires more of a theory...
  20. U

    Help understanding this Kinetic energy problem

    although I dont understand the question properly , they did say in ithe question the skater does 300J of work, so it looks liek you'd be on the right track rcgld "By my math, the skater does about 296.37728 J of work." I just have no ideas if my answers are on the right path or not.
  21. U

    Help understanding this Kinetic energy problem

    Homework Statement A 60kg ice skater is spinning around at 300 degrees per second. His radius of gyration is .5m. As he pulls his arms in he does 300 J of work. i.What is his initial kinetic energy? ii.What is his final kinetic energy ? iii.Assuming that his new radius of gyration is .32m...
  22. U

    Impulse and momentum question, relates to Biomechanics

    yes this is where I'm confused...how do you incorporate g into it ?
  23. U

    Impulse and momentum question, relates to Biomechanics

    to the best of my knowledge yes, I have literally written out the question as it was presented.
  24. U

    Impulse and momentum question, relates to Biomechanics

    Homework Statement A male and female pair of dancers start dancing when the male lifts the female and throws her into the air. The female's mass is 40kg . The male exerts an average vertical force of 500n for 1.0s on the female. What is her vertical velocity when she is released into the air...
  25. U

    Buoyant force in seawater and freshwater

    ohh I'm definitely confused.... oli4 makes mention of the fact that if I submerge an object in freshwater or seawater then the volume displaced will be identical. I believe this is due to the fact that the object has been submerged. I guess it's different in the case of a boat floating ? In...
  26. U

    Buoyant force in seawater and freshwater

    Homework Statement I'm doing a problem that is likely a common one. It is comparing the buoyant force of an object in seawater to that of the same object in freshwater. which has more buoyant force acting on it? Homework Equations not sure of equations at this stage, and we are just...
  27. U

    Help understanding dynamic equilibrium

    hmmm I dont quite get what would make the box slide ? If ƩF=0 and there's no friction my guess would be there is no force...but then I don't get how the box would be sliding with no force on it
  28. U

    Help understanding dynamic equilibrium

    Homework Statement if the equilibrium rule states ƩF=0N, how can something move or be moving at a constant speed ? eg I push on a box with 50N and friction provides 50N back, resulting in ƩF=0N. So I am not providing more N than the box is resisting with. I thought something could only be...
  29. U

    What is the point of angling projectiles?

    Homework Statement If the horizontal velocity remains the same, whether angled or not, I dont quite understand why we bother launching projectiles upwards on an angle? Would it be better just to launch them horizontally ? Homework Equations d= 1/2gt^2....I think? The Attempt at...
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