Recent content by kenji1992

  1. K

    Kinematics - projectile motion - time to maximum height?

    I don't know. I remember someone in class saying that projectile motion was a parabola... t=1.0 s means what? The time it takes for the motion to finish? or the time at which the water reaches its maximum height?
  2. K

    Kinematics - projectile motion - time to maximum height?

    1.02 s is not an option for this multiple choice problem, the closest is 1.0 s. Is that likely the answer then? Edit: The question asks how long it takes to reach maximum height, so because it is a parabola, it stands to reason that 1.02s/2=0.51s is how long it takes to reach the maximum...
  3. K

    Kinematics - projectile motion - time to maximum height?

    I tried this: Vfy=Viy+Ay*t 0 m/s=10 m/s-9.8 m/s^2*t -10 m/s=-9.8 m/s^2 *t t=10 m/s / -9.8 m/s^2 t=1.02 s
  4. K

    Kinematics - projectile motion - time to maximum height?

    Kinematics -- projectile motion -- time to maximum height? Homework Statement The nozzle of a fire hose discharges water at a speed of 10 m/s. The nozzle is aimed straight up. How long does it take for a water drop to reach its maximum height? Start with translating the question: vi= 10 m/s...
  5. K

    Kinematics - How fast does the car stop?

    d=0.5(vi+vf)*t d=0.5(0 m/s + 32 m/s)*9.14 s d=146.24 m
  6. K

    Kinematics - How fast does the car stop?

    Kinematics -- How fast does the car stop? Homework Statement A car is moving with a speed of 32.0 m/s. The driver sees an accident ahead and slams on the brakes, giving the car an acceleration of -3.50 m/s2. How far does the car travel after the driver put on the brakes before it comes to a...
  7. K

    Can You Catch a Falling Dollar Bill with Your Reaction Time?

    y(t) = vi*t - 1/2gt^2 0.16m = 0m/s*t - 1/2*9.8 m/s^2*t^2 0.16 m=4.9 m/s^2 *t^2 0.16 m/4.9 m/s^2 = t^2 t=0.18 s so then theoretically i could not catch the dollar bill? right?
  8. K

    Can You Catch a Falling Dollar Bill with Your Reaction Time?

    Oops, I typed the wrong formula. In my text, it shows that it is y(t)=yi +vi*t -(1/2)gt^2 What do i do about the yi?
  9. K

    Can You Catch a Falling Dollar Bill with Your Reaction Time?

    Would I use this formula: y(t) = vi*t - 1/2gt^2 0.16m = 0m/s*t - 1/2*9.8 m/s^2*t^2 0.16 m=4.9 m/s^2 *t^2 0.16 m/4.9 m/s^2 = t^2 then square it?
  10. K

    Can You Catch a Falling Dollar Bill with Your Reaction Time?

    d=16cm a=9.8 m/s^2 (would this be negative?) t=?
  11. K

    Can You Catch a Falling Dollar Bill with Your Reaction Time?

    Homework Statement Your friend makes a wager with you. He holds a $50 bill between your thumb and finger, and says you can keep the $100 bill if you can catch it when it drops. The bill is 16cm long. Using your reaction time do you catch the bill? Homework Equations The Attempt...
  12. K

    2D Kinematics - 2 rocks off a bridge

    2D Kinematics -- 2 rocks off a bridge Homework Statement Heather and Jerry are standing on a bridge 60m above a river. Heather throws a rock straight down with a speed of 14m/s . Jerry, at exactly the same instant of time, throws a rock straight up with the same speed. Ignore air...
  13. K

    Vectors - velocity is changing but speed is not

    #C, D, E can't be correct then by that logic... I hope I'm interpreting that correctly.
  14. K

    Vectors - velocity is changing but speed is not

    Vectors -- velocity is changing but speed is not... Homework Statement Which pair of vectors represent an object whose velocity is changing but whose speed is NOT changing? Homework Equations The Attempt at a Solution E? V is going left, indicating negative, while acceleration...
  15. K

    Kinematics - centrifuging a solution with bacteria

    Magnitude means measurement, right?
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