Forces, Moments and Accelerations of Rigid Bodies
(Planar)
Key equations
There is an F = ma equation, valid for a in an inertial frame at the COM, and a moment
balance equation (Newtons 2nd law, or Newton/Euler law). For planar motion, we have
F = ma G
(
PROBLEM 11.8
The motion o f a particle is defined b y the relation
x := 2t3 18t 2 + 4 8t 16, where x a nd t are expressed i n millimeters
and seconds, respectively. Determine (a) w hen the velocity is zero,
(b) t he position and the total distance travele
PROBLEM 11.18
Point A oscillates with an acceleration a = 144(20 - x), where a and x
are expressed i n in.ls2 and inches, respectively. Knowing that the system
starts at time 1 = 0 with v = 0 and x = 19 in., determine the position and
the velocity o f A w
PROBLEM 11.110
.~"'~.'~_~0il'",'~c"~"~"5;'~"'"> A golfer hits a ball with an initial velocity o f magnitude Vo a t a n angle a
w ith the. horizontal. Knowing that the ball must clear the tops o f two trees
a ndJand as close as possible to the flag, determ
PROBLEM 12.18
The system shown is initially at rest. Neglecting the masses o f the pulleys
and the effect o f friction i n the pulleys, determine (a) the acceleration o f
each block, (b) the tension in each cable.
10 kg
SOLUTION
Let Y be positive downwar