Question 6
A rack and pinion is used to open a sliding gate.
Which motion conversion takes place?
That is it. Step through the hints below to see why.
Not quite. You have confused linear with reciprocating motion. The gate makes one straight-line movement, not a continuous back-and-forth one.
Not quite. You have confused rotary with oscillatory motion. The pinion turns, it does not swing back and forth.
Not quite. You have reversed the input and the output. The drive turns the pinion (the input), and the rack moves the gate (the output).
Black: the gate, its rack and the pinion on the motor. Orange dashed: the motion the option you are testing claims for the pinion (the input) and for the gate (the output).
The pinion turns about its axle and the gate slides one way in a straight line. Rotary in, linear out: this option matches.
The gate slides once, in one direction, and stops. It does not keep moving back and forth, so its motion is linear, not reciprocating. Closing it later is a separate movement with the motor reversed.
The pinion keeps turning the same way through most of a turn. It does not swing back and forth through an arc, so its motion is rotary, not oscillatory.
The motor turns the pinion and the pinion drives the rack and gate. Linear to rotary has the input and the output the wrong way round.
Start with the part the drive turns. The pinion rotates, so the input is rotary motion.
The drive turns the pinion.
The pinion’s teeth push the rack, and the rack is fixed to the gate. The rack and gate move in a straight line, so the output is linear motion.
Rotary motion to linear motion is option (A).
The gate only slides one way as it opens.
The pinion rotates (rotary input), and the rack and gate move in a straight line (linear output).
The past QCAA questions this one was modelled on
Only mark this done when you could do it without help. Reading the solution does not count.
A Tangent Tuition mock exam question. It is not a past QCAA question, and Tangent Tuition is not affiliated with the QCAA.
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