| 4kg----------------------------------------------------3kg | | | Axis is in th
ID: 2103434 • Letter: #
Question
|4kg----------------------------------------------------3kg
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Axis is in the middle and everything is moving counter clockwise.
A 4.0 kg mass and a 3.0 kg mass are attached to the opposite ends of a thin 42.0 cm long horizontal rod (see picture). The system isrotating at angular speed ?=5.50 rad/s about a vertical axle in thecenter of the rod. Determine (a) the Kinetic Energy of the system,and (b) the net force on each mass. Repeat parts (a) and (b) assuming that the axle passes through the center of mass of the system. |
4kg----------------------------------------------------3kg
|
|
|
Axis is in the middle and everything is moving counter clockwise.
A 4.0 kg mass and a 3.0 kg mass are attached to the opposite ends of a thin 42.0 cm long horizontal rod (see picture). The system isrotating at angular speed ?=5.50 rad/s about a vertical axle in thecenter of the rod. Determine (a) the Kinetic Energy of the system,and (b) the net force on each mass. Repeat parts (a) and (b) assuming that the axle passes through the center of mass of the system.
Explanation / Answer
KE = 0.5Mw^2 r^2 = 0.5(3+4) 5.5^2 * 0.21^2= 4.668 J
b) F4 = mw^2 r = 4 x 5.5^2 x 0.21 = 25.41 N
F3 = 3 x 5.5^2 x 0.21 = 19.057 N
about cm
cm = 4*42/(4+3) i.e. 24cm from 3kg mass
so KE = 0.5 x 4 x 5.5^2 x 0.18^2 + 0.5 x 3 x 5.5^2 x 0.24^2 = 4.573 J
F4 = mw^2 r' = 4 x 5.5^2 x 0.18 = 21.78N
F3 = 3 x 5.5^2 x 0.24 = 21.78 N
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