|File:Chamber 5 PeTI 1.png|alt3=Alternative version of the Test Chamber made in [Puzzle Creator (see Trivia)|Alternative version of the Test Chamber made in [[Puzzle Creator]] (see [[#Trivia|Trivia]]).
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Chapter 1 - Test Chamber 05
sp_a1_intro5.bspCube Momentum
This is the fifth level in the game and, like the other early levels, is set within a dilapidated Test Chamber. It introduces the player to some of the basic principles behind Portal physics, namely the way in which speed and momentum can be used in combination with Portals. Panels are also introduced in this level, and are are activated through the use of Buttons. Finally, the first environmental hazard, Goo, is introduced in order to add a consequence for failure.
Place the newly acquired cube onto the Heavy Duty Super-Colliding Super Button to activate the panel-based staircase to the left; ascend these stairs to reach two buttons.
The button to the left controls an apparatus vent, the button to the right controls a large panel which will rotate 90° clockwise. Press the left button first and then place a portal on the platform below the vent. The button to the right should then be pressed as the cube is leaving the vent in order to halt the cube after it has passed through the portal.
Bring this cube up to the second Button in order to open the door to the Chamberlock.
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