Swingset
Swingset
[Woman talking to Cueball on swing-set.] Woman: You know, at the peak of a big swing, you become weightless. [Thought bubble from Cueball.] [Cueball swings higher and higher. At the peak of a big swing, he shoves himself off the swing. Cueball remains hovering in the air.] Cueball: Hey guys. Come check this out.

In the opening panel of this comic, Blondie , possibly as Miss Lenhart , sees Cueball sitting on a swing set. She tells him that during his swing, he becomes weightless. Cueball then imagines that at the peak of his swing he is able to become permanently weightless, floating above the ground without any support.
When on a swing or other pendulum ride , there is a moment between swinging forwards/backwards and swinging back down again when the forces of gravity, friction, air resistance, etc., bring the velocity of the swing to zero. At this moment, there is no acceleration toward the pivot of the swing (since the centripetal acceleration is proportional to the square of the speed). So the swinger experiences no centripetal force. Of course, gravity still acts on the person, but if the swing is horizontal at that point, then there is no reaction force, so for one moment, the swinger is in free-fall and experiences weightlessness . However, that weightlessness can only be maintained for a fraction of a second, so if Cueball tried this in real life, he would come crashing to the ground.
In the title text, Cueball asks for a pocket fan, believing he could fly around the yard using this small device perhaps as a propeller.
[Woman talking to Cueball on swing-set.] Woman: You know, at the peak of a big swing, you become weightless. [Thought bubble from Cueball.] [Cueball swings higher and higher. At the peak of a big swing, he shoves himself off the swing. Cueball remains hovering in the air.] Cueball: Hey guys. Come check this out.
