Problem: Allan sat down at his desk and pulled the chair in close. Opening a side drawer, he took out a piece of paper and his inkpot. After filling his pen, Allan looked at his paper in the orange glow from the lantern set back in the desk's right-hand corner. His pen cast a forbidding line of shadow slanting across the page, echoing the inky darkness crouching in the edges of the lantern's struggling glow. The only other illumination came from a lurid moonlight filtered through thin branches and clouds, casting its bone-pale glow onto the pine floorboards. Allan unfolded another page, this one crowded with ranks of letters in tight formation from left to right. The lines of letters stepped into their divisions, in the shape of a story's outline: the loose, dry skeleton of a tale lay exposed beneath their feet, awaiting tendons, muscle and blushing skin. Allan reviewed the troops, all prepared to disembark, their task to form the tale of a young man returning home from Life Abroad to find his childhood friend a bride to-be, thus upsetting the apple cart of his life's plan, clarified of course by his very time away from her he loved best. Although the concept was a simple one, Allan thought it had potential. Besides, the public liked a good, simple romance. Perhaps this will be more saleable, he thought and began to write. They gazed at each other, lost in the rapture of love based so deeply within their hearts that they had never seen it before. "What about Roger?" she asked, knowing that the answer no longer mattered.

Question: "What are the two light sources Allan is using to write?"

Answer: "Lantern light and moonlight"
Answer: yes

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: "Does size matter as to whether or not an object has gravity?"

Answer: "no"
Answer: yes

Problem: If you have a mass of 50 kg on Earth, what is your weight in newtons? An object with more mass is pulled by gravity with greater force. Mass and weight are closely related. However, the weight of an object can change if the force of gravity changes. On Earth, the force of gravity is the same everywhere. So how does the force of gravity change? It doesnt if you stay on Earth. What if we travel to another planet or moon in our solar system? Look at the photo of astronaut Edwin E. Aldrin Jr. taken by fellow astronaut Neil Armstrong in the Figure. They were the first humans to walk on the moon. An astronaut weighs less on the moon than he would on Earth. This is because the moons gravity is weaker than Earths. The astronauts mass, on the other hand, did not change. He still contained the same amount of matter on the moon as he did on Earth. If the astronaut weighed 175 pounds on Earth, he would have weighed only 29 pounds on the moon. If his mass on Earth was 80 kg, what would his mass have been on the moon? [Figure 3]

Question: "What's the difference between weight and mass?"

Answer: "Weight never changes"
Answer:
no