smc-3730-70-Transport

One of several fail-safe systems incorporated into a roller coaster design uses the following safety protocol.

Before a roller coaster car brake can be released to allow the roller coaster to commence its ride, ALL of the following conditions must be met:

- passenger safety harnesses must be secured into place
- the sensors must indicate the track is clear of obstructions
- the ride entry and exit gates are locked.

A logic gate schematic is shown.

What is the purpose of the NAND gate in this schematic? (2 marks)

--- 5 WORK AREA LINES (style=lined) ---
Complete the truth table for the logic gate schematic. (3 marks)

--- 0 WORK AREA LINES (style=lined) ---

\begin{array} {|c|c|c|c|}
\hline
\rule{0pt}{2.5ex} \textit{Safety harnesses} \rule[-1ex]{0pt}{0pt} & \textit{Track} & \textit{Ride gates are} & \textit{Operator} \\ \textit{secure} & \textit{is clear} & \textit{locked} & \textit{warning light} \\
\hline
\rule{0pt}{2.5ex} 0 \rule[-1ex]{0pt}{0pt} & 0 & 0 & \\
\hline
\rule{0pt}{2.5ex} 0 \rule[-1ex]{0pt}{0pt} & & & 1 \\
\hline
\rule{0pt}{2.5ex} 0 \rule[-1ex]{0pt}{0pt} & 1 & 0 & 1 \\
\hline
\rule{0pt}{2.5ex} 0 \rule[-1ex]{0pt}{0pt} & & & \\
\hline
\rule{0pt}{2.5ex} 1 \rule[-1ex]{0pt}{0pt} & 0 & 0 & 1 \\
\hline
\rule{0pt}{2.5ex} 1 \rule[-1ex]{0pt}{0pt} & & & 1 \\
\hline
\rule{0pt}{2.5ex} 1 \rule[-1ex]{0pt}{0pt} & & & 1 \\
\hline
\rule{0pt}{2.5ex} 1 \rule[-1ex]{0pt}{0pt} & 1 & 1 & \\
\hline
\end{array}

Show Answers Only

i. NAND gate purpose:

→ Ensures that if any or all of the inputs are zero the output will result in a 1 and thus turn on the warning light.

→ In effect, the warning light will remain ON until all conditions for safe operation are met.

ii.

\begin{array} {|c|c|c|c|}
\hline
\rule{0pt}{2.5ex} \textit{Safety harnesses} \rule[-1ex]{0pt}{0pt} & \textit{Track} & \textit{Ride gates are} & \textit{Operator} \\ \textit{secure} & \textit{is clear} & \textit{locked} & \textit{warning light} \\
\hline
\rule{0pt}{2.5ex} 0 \rule[-1ex]{0pt}{0pt} & 0 & 0 & 1 \\
\hline
\rule{0pt}{2.5ex} 0 \rule[-1ex]{0pt}{0pt} & 0 & 1 & 1 \\
\hline
\rule{0pt}{2.5ex} 0 \rule[-1ex]{0pt}{0pt} & 1 & 0 & 1 \\
\hline
\rule{0pt}{2.5ex} 0 \rule[-1ex]{0pt}{0pt} & 1 & 1 & 1 \\
\hline
\rule{0pt}{2.5ex} 1 \rule[-1ex]{0pt}{0pt} & 0 & 0 & 1 \\
\hline
\rule{0pt}{2.5ex} 1 \rule[-1ex]{0pt}{0pt} & 0 & 1 & 1 \\
\hline
\rule{0pt}{2.5ex} 1 \rule[-1ex]{0pt}{0pt} & 1 & 0 & 1 \\
\hline
\rule{0pt}{2.5ex} 1 \rule[-1ex]{0pt}{0pt} & 1 & 1 & 0 \\
\hline
\end{array}

Show Worked Solution

i. NAND gate purpose:

→ Ensures that if any or all of the inputs are zero the output will result in a 1 and thus turn on the warning light.

→ In effect, the warning light will remain ON until all conditions for safe operation are met.

ii.

\begin{array} {|c|c|c|c|}
\hline
\rule{0pt}{2.5ex} \textit{Safety harnesses} \rule[-1ex]{0pt}{0pt} & \textit{Track} & \textit{Ride gates are} & \textit{Operator} \\ \textit{secure} & \textit{is clear} & \textit{locked} & \textit{warning light} \\
\hline
\rule{0pt}{2.5ex} 0 \rule[-1ex]{0pt}{0pt} & 0 & 0 & 1 \\
\hline
\rule{0pt}{2.5ex} 0 \rule[-1ex]{0pt}{0pt} & 0 & 1 & 1 \\
\hline
\rule{0pt}{2.5ex} 0 \rule[-1ex]{0pt}{0pt} & 1 & 0 & 1 \\
\hline
\rule{0pt}{2.5ex} 0 \rule[-1ex]{0pt}{0pt} & 1 & 1 & 1 \\
\hline
\rule{0pt}{2.5ex} 1 \rule[-1ex]{0pt}{0pt} & 0 & 0 & 1 \\
\hline
\rule{0pt}{2.5ex} 1 \rule[-1ex]{0pt}{0pt} & 0 & 1 & 1 \\
\hline
\rule{0pt}{2.5ex} 1 \rule[-1ex]{0pt}{0pt} & 1 & 0 & 1 \\
\hline
\rule{0pt}{2.5ex} 1 \rule[-1ex]{0pt}{0pt} & 1 & 1 & 0 \\
\hline
\end{array}

ENGINEERING, TE 2023 HSC 24d

ENGINEERING, TE 2018 HSC 21d