Question
A particle travels counterclockwise around the origin at constant speed in a circular path that has a diameter of 2.50 m, going around twice per second. Point Q is on the path halfway between points P and R, which lie on the x axis and the y axis, respectively. State the following velocites as vectors in polar notation. (a) What is the particle's average velocity over the interval PR? (b) What is its average velocity over the interval PQ? (c) What is its instantaneous velocity at point P?
P coordinates: (1.25, 0)
R coordinates: (0, 1.25)
Q is directly between the two
P coordinates: (1.25, 0)
R coordinates: (0, 1.25)
Q is directly between the two
Answers
frequency f = 2 rev/s
angular velocity = 2•π•f = 4•π rad/s
(a) Velocity vector at P = (1.25x4x3.14)j = 15.7 j,
where j is unit vector along positive y axis.
Also velocity vector of the particle at R = -15.7i,
where i is unit vector along positive x direction.
As the direction changes uniformly,
the average velocity over the interval PR is
(15.7/2)(j-i)= 7.85(j-i).
Magnitude = sqrt[7.85^2+7.85^2] =
=1.414x7.85 = 11.10 m/s
and the direction is 45 degrees west of north.
(b) Average velocity, V1 over interval PQ is
= 0.5{15.7 j + [15.7/sqrt(2)](j-i)} or
V1 = 0.5[26.80 j - 11.10i] = 13.40 j - 5.55 i.
Magnitude of V1 = sqrt[13.40^2 + 5.55^2] = 14.50 m/s.
due theta west of north given by theta = tan^-1 [5.55/13.40] = 22.5 degrees west of north.
(c) v= 2•π•f•R = 15.7 m/s due north
Related Questions
The particle travels along the path defined by the parabola y=0.5(x^2). If the component of velocity...
A particle travels between two parallel ver-
tical walls separated by 39 m. It moves to-
ward the...
A particle travels along the x-axis so that its velocity is given by v(t)=cos3x for 0<(or equal to)t...
A particle rotates counterclockwise in a circle of radius 6.5 m with a constant angular speed of 7.4...
A particle travels along the curve c(t) = (6t^3-6, 7t^2-4). If time t is measured in seconds and if...
A particle travels along the x axis with a constant acceleration of +2.7 m/s2. At a time 4.2s follow...
A particle travels along the parabola y=ax^2+x+b. At what point do its abscissa and ordinate change...
A particle travels between two parallel ver- tical walls separated by 12 m. It moves to- ward the op...
A particle rotates counterclockwise from rest according to 8 = tl S0 - i, where 6 is in radians
and...