Once upon a time, there was a little girl named Nikki who loved to play with her ball. She would bounce it, roll it, throw it and catch it. She had so much fun with her ball.
One day, she decided to take her ball to the park. There was a big hill in the park that she liked to climb. She thought it would be fun to roll her ball down the hill and watch it go fast.
She climbed up the hill with her ball and placed it on the top. She gave it a gentle push and watched it roll down. She was amazed by how fast it went. “Wow!” she said. “My ball is so fast!” She ran down the hill to get her ball and climbed up again. She wanted to try again. She placed her ball on the top of the hill and pushed it harder this time. She watched it roll down even faster than before. “Wow!” she said again. “My ball is super fast!” She ran down the hill again and climbed up for the third time. She wanted to make her ball go as fast as possible. She placed her ball on the top of the hill and pushed it with all her strength. She watched it roll down with incredible speed. “Wow!” she said for the third time. “My ball is super duper fast!” But then, something unexpected happened. Her ball hit a rock at the bottom of the hill and bounced up in the air. It flew over Nikki’s head and landed behind her. “Uh-oh!” she said. “Where did my ball go?” She turned around and saw her ball lying on the ground. She ran towards it and picked it up. She was puzzled by what had happened. How did her ball go so fast and then fly so high? She decided to ask her father, who was sitting on a bench nearby.
“Papa, can you explain something to me?” she asked. “Sure, Nikki, what is it?” he replied.
“How did my ball go so fast when I rolled it down the hill? And how did it fly so high when it hit the rock?” she asked.
“Well, that’s a good question,” he said. “Do you know what energy is?”
“Energy?” she repeated. “No, what is that?”
“Energy is something that makes things move or change,” he explained. “There are different kinds of energy, but I’ll tell you about two of them: potential energy and kinetic energy.”
“Potential energy and kinetic energy?” she repeated again.
“Yes,” he said. “Potential energy is energy that is stored in something because of its position or shape. Kinetic energy is energy that something has because of its motion.”
“I don’t get it,” she said.
“Let me give you an example,” he said. “When you placed your ball on the top of the hill, it had potential energy because of its position. It was high up, so it could fall down.”
“Oh, I see,” she said.
“When you pushed your ball, you gave it some kinetic energy because of its motion. It started to roll down the hill,” he continued.
“OK, I get that,” she said.
“As your ball rolled down the hill, it lost some potential energy because it got lower, but it gained more kinetic energy because it got faster,” he explained.
“So that’s why my ball went faster and faster?” she asked.
“Yes, exactly,” he said. “And when your ball hit the rock, something else happened. Some of its kinetic energy was transferred to another kind of energy: elastic potential energy.”
“Elastic potential energy?” she repeated once more.
“Yes,” he said. “Elastic potential energy is energy that is stored in something because of its shape. When your ball hit the rock, it got squished a little bit, like a spring. That gave it some elastic potential energy.”
“Oh, I see,” she said again.
“So that’s why my ball flew so high?” Nikki asked.
“Then, your ball bounced back to its original shape and released its elastic potential energy as kinetic energy again,” he finished.
“Yes, exactly,” he said again. “And then your ball fell back to the ground and lost all its kinetic energy.”
“I think I understand now,” Nikki said.
“That’s great,” he said. “You just learned about potential energy and kinetic energy.”
“Thank you for explaining them to me, Papa,” she said. “You’re welcome, Nikki,” he said. “
Short stories for kids 