Unformatted text preview: ME 240
– 17.5 – General Motions: Accelerations • For Monday
– HW (due 11/8): 17.93, 17.99 – Supplemental: 17.86, 17.89, 17.116 General Motion: Summary
Velocity of points on a rigid body: v A vB v A / B v A vB rA / B Acceleration of points on a rigid body: aA aB aA /B aA aB rA /B ( rA /B ) 2 aA aB rA /B rA /B Simple Rolling Motion ‐ Acceleration
To analyze rolling motion acceleration we need a point of known acceleration 2 aA aB rA / B rA / B The wheel center, point C, is convenient to use ˆ Velocity of point C: v v r vC ri C O C /O d d ˆ ˆ Acceleration of point C: a vC dt ri ri C dt Problem 17.85. Magnitude of the velocity and acceleration of point C are 2m/s and 14m/s2. A is moving and accelerating toward right. • Determine accelerations of B and D 5‐30 Example: The disk shown is rolling without slip on the circular surface shown. The angular velocity and angular acceleration of the disk are D D given as and , respectively. Determine the velocity and acceleration of point C 5‐31 Example: At the instance shown, bar AB is rotating at 10 rad/s in the CCW direction and has a CCW angular acceleration of 20 rad/s2. The disk rolls without slip on the circular surface. Determine the angular acceleration of bar BC and the disk 5‐32 Example of a 4‐Bar Linkage Four bar linkage in above‐ knee prosthetics have been designed to mimic real knee motion 4 bar linkage for a prosthetic knee design Coordinates (mm): A(0,0); B(‐27,120), C(26, 124), D(30,15) Given: AB=1.5 rad/sec k, AB=0.8 rad/sec2 k Determine: BC, CD, BC, CD, aP 5‐34 ...
View Full Document
- Spring '08
- Angular Acceleration, rA /B, CCW angular acceleration