Problem: So what is gravity? A typical definition of gravity is that it is a force. It causes an attraction between two masses. According to this definition, anything that has mass exerts a force. Any object exerts gravity on other objects. It does not matter how small it is, it has gravity. The more matter an object has, the more gravity it has. Your pencil has a tiny bit of gravity, but far too little to notice. What about a planet? It would have a lot of gravity. An objects gravity exerts a pull on other objects. Friction only occurs between objects that are touching. Gravity can act between objects that are not touching. In fact, gravity can act over very long distances. Where else can you feel gravity?

Question: "What would keep gravity from affecting two objects?"

Answer: "distance"
Answer: yes

Problem: Sara wanted to play on a baseball team. She had never tried to swing a bat and hit a baseball before. Her Dad gave her a bat and together they went to the park to practice. Sara wondered if she could hit a ball. She wasn't sure if she would be any good. She really wanted to play on a team and wear a real uniform. She couldn't wait to get to the park and test out her bat. When Sara and her Dad reached the park, Sara grabbed the bat and stood a few steps away from her Dad. Sara waited as her Dad pitched the ball to her. Her heart was beating fast. She missed the first few pitches. She felt like quitting but kept trying. Soon she was hitting the ball very far. She was very happy and she couldn't wait to sign up for a real team. Her Dad was very proud of her for not giving up.

Question: "Who pitched the ball to Sara and where did it occur?"

Answer: "Her dad in the backyard"
Answer: no

Problem: Renewable Energy Resource Sunlight Sunlight can be used to heat homes. It can also be used to produce electricity. This conversion is made possible by solar cells. However, solar energy may not always be practical. Some areas are just too cloudy. Example Solar panels on the roof of this house generate enough electricity to supply a familys needs. Moving Water Falling water can have a lot of energy. Its energy can be converted into kinetic energy. This energy can turn a turbine and generate electricity. The water may fall naturally over a waterfall or flow through a dam. A drawback of dams is that they flood land upstream. They can also reduce water flow downstream. Either effect may harm ecosystems. Wind Wind is moving air. It has kinetic energy that can do work. Wind turbines change the kinetic energy of the wind to electrical energy. Only certain areas of the world get enough steady wind. Many people also think that wind turbines are noisy and not very nice to look at.

Question: "What are 3 sources of renewable energy"

Answer: "Renewable energy comes from moving water, the sun and petroleum"
Answer:
no