General Planar Motion - Example Problem 4.3-4

Consider the following diagram of a piston assembly in an internal combustion engine. The crankshaft OA is rotating at a constant rate of 2000 rpm counter-clockwise. If the piston is at top dead center position (θ = 0^o), determine ...

1. the velocity of the piston head B,
2. the angular velocity of the connecting rod AB, and
3. the angular acceleration of the connecting rod AB.

Given:

• ω_OA = 2000 rpm ccw = constant
• θ = 0^o
• l_OA = 0.1 m
• l_AB = 0.2 m

Find:

1. v_B
2. ω_AB
3. α_AB

The following video walks you through the solution to this problem. It is suggested that you try solving the problem first and then, if you have difficulties with the solution, watch the video for help.

Familiarize yourself with the system.

• Note fixed point O.
• Assign the directions of the angular velocities and angular accelerations.
• Note that piston B is constrained to move only up and down.

Click on the figure after you have familiarized yourself with the system and drawn a schematic illustration.

Analyze the motion of link OA. Find the velocity of joint A. Which equation should be used?