- #1
Husker70
- 90
- 0
Homework Statement
Suppose the positon vector for a particle is given as a function of time by vector r(t)
=x(t)i + y(t)j with x(t) =at + b and y(t) = ct2 + d, where a=1.00 m/s, b=1.00m,
c=.125 m/s2, and d=1.00m. (a) Calculate the average velocity from t=2.00s to t=4.00s.
(b) Determine the velocity and the speed at t=2.00s
Homework Equations
(a) plug in the values for a, b, c, and d to
x(t) = at + b and y(t) = ct2 + d
Vavg = delta r / delta t
3. The Attempt at a Solution [/c]
(a) Ri =
x(t) = (1.00m/s) 2.00s + 1.00m = 3.00 m/s
y(t) = (.125m/s2) 2.00s2 + 1.00m = 2.41 m/s
Rf
x(t) = (1.00m/s) 4.00s + 1.00m = 5m/s
y(t) = (.125m/s) 4.00s2 + 1.00m = 6.66m/s
Rf -Ri / Tf - Ti
Rf = 6.66 - 2.41 = 4.25
Ri = 5 - 3 = 2
t = 2
4.25 - 2 /2 = 1.13 Vavg from t = 2 to t=4
(b) From equation at 2 s
velocity is
x(t) = 2.41
y(t) = 3
velocity is 5.41 m/s at t=2
Speed is magnitute of vector square root of (3)2 + (2.41)2 = square root of 14.81
Speed = 3.85 m/s
Am I right or close?
Thanks for the help
Kevin