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The crank of a slider-crank mechanism rotates counter -clock wi se (CCW) with a const ant angular velocity ω, as shown. Assume the length of the crank to be r .
Using exact analysis, the acceleration of the slider in the y-direction, at the instant shown, where the crank is parallel to x-axis, is given by
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- – ω&dup2;r
- 2ω&dup2;r
- ω&dup2;
- – 2ω&dup2;r
Correct Option: C
Exactly analysis means exact dimensions have to be taken. No approximation is allowed. It means velocity diagram and acceleration diagram with exact geometry (dimensions) need to be drawn. 
The velocity diagram of the above problem is as follows: 
op perpendicular to OP
oq in the direction of movement of slider.
Since, p, q are coinciding i.e. no relative motion between p and q
VP = VQ = rω
and, Vqp = 0 and ωqp = 0
∴ There will be no radial acc. of link PQ.
Only tangential acc.(atqp will be there.
Also for link OP, α = 0 i.e. no tangential acceleration 
| tan 45° = | |
| rω |
⇒ aq = rω²
