Chapter 1 — The Cart That Did Not Want to Stop Yet

Wong Nam tucked the shopping list into his shirt pocket, and Iota caught the top corner of the paper before it disappeared inside.

“Bread, milk, bananas,” Iota read aloud. “May we get cereal too?”

“We may. Tomorrow morning we will have cereal for breakfast together.”

“I will set out the two bowls myself!”

They walked into the supermarket. Right by the entrance, Wong Nam pulled out an empty shopping cart. The cart stood completely still on the tile floor until Iota laid both hands on the handlebar and pushed.

Four small wheels spun beneath the wire basket as the cart rolled forward. Wong Nam walked alongside her, close enough to steady the frame if the cart veered to the side.

The first aisle was wide and empty. Iota pushed the cart until it was gliding smoothly along the tiles, and then she lifted both hands clean off the handlebar.

The cart kept rolling forward on its own, its four wheels still spinning.

Walking right behind it with her hands raised in the air, Iota watched the cart roll a little farther, slower and slower. Before the nose of the basket could reach the end of the shelving rack, Wong Nam caught the side of the frame and brought it to a stop.

“Grandpa, I already let go with both hands,” Iota said. “Why didn’t the cart stop the instant I let go?”

“Think back for a second. While you were pushing, which way was the cart moving?”

“Forward.”

“And the moment you took your hands off the bar?”

“Still forward.” Iota frowned slightly. “Only it got slower and slower until it stopped.”

Wong Nam waited until no other shoppers were passing through the aisle, then invited Iota to crouch down beside the cart where they could see one of the front wheels up close.

Iota gave the cart another tiny push and let go. The small wheel turned, slowed down, and came to rest.

“Something is making the cart slow down,” Iota said.

“What do you think it is?”

Iota looked at the rubber wheel resting against the floor tiles. “The wheels and the floor. They keep rubbing against each other.”

“Along with the parts inside the axle rubbing against one another,” Wong Nam said. “That rubbing is called friction, and it holds the cart back little by little.”

Iota stood up and looked at the shopping cart with fresh eyes. The cart did not stop because her hands let go. It stopped because friction kept holding it back.

“Now for the milk,” Wong Nam said.

Iota lifted two cartons of milk from the cooler and laid them side by side flat on the bottom of the basket near the front. The coated cardboard of the milk cartons was smooth and slick. After Wong Nam picked out a loaf of bread, they walked over to the cereal aisle.

Standing before the shelves, Iota read the names across the boxes and chose one covered in tiny yellow stars.

She laid the cereal box flat on top of the two milk cartons. It rested there quietly without anything wedging it in place, a good handspan back from the front grille of the basket.

Nobody knew that the cereal box would soon slide forward.