What if two children push a swing at the same time? Would the swing go higher? Yes, together their force would be more. It is common for forces to be combined. Most objects on Earth have at least two forces acting on them. Do you know what one of them is? Of course, that force is gravity. How many forces do you have on you right now? Gravity pulls you down toward the center of Earth. Your legs exert a downward force. They hold you up against the pull of gravity. Consider the example in Figure 1.3. A book is resting on a table. Gravity pulls the book downward. It has a force of 20 newtons. At the same time, the table pushes the book upward. Its force is also 20 newtons. The table opposes the pull of gravity.
What question would one ask from this paragraph?
Answer: Which forces affect a book resting on a table?

Dr. Alex Cross is a psychiatrist and police lieutenant who lives in Detroit with his wife , Maria , their children , Damon and Janelle , and his grandmother , Nana Mama . Upon learning that Maria is pregnant with their third child , Cross considers accepting a job as an FBI profiler , but fears Maria's reaction , as it 'd require them to relocate to Washington , D.C. Meanwhile , a man called Picasso attends to an illegal underground Mixed Martial Arts fighting ring , where he flirts with businesswoman Fan Yau . After brutally beating his opponent , Picasso is invited to Fan Yau's house , where he sedates her while they 're having sex , tortures and kills her . Police Captain Richard Brookwell calls Cross and his partner , Tommy Kane , to the crime scene . On the way there , Cross tells Kane about Maria's pregnancy and the the FBI's offer , and Kane reveals that he is secretly dating their colleague , Monica Ashe . Cross deduces that Picasso is a professional assassin , and finds a sketch made behind by Picasso , revealing that his next target is businessman Erich Nunemarcher . Cross , Kane and Ashe go to Nunemarcher's office , but Nunemarcher ignores their claims . Picasso manages to enter the building , but is prevented from killing Nunemarcher by Cross , and escapes after being shot by Kane . Cross analyzes a drop of Picasso's blood and learns that he is a psychotic former member of the Special Forces and that his real target is billionaire CEO Leon Mercier . Cross informs Mercier that Picasso might be trying to kill him .
What question would one ask from this paragraph?
Answer: Who were all of Picasso's real and possible targets?

Mechanical energy is a combination of the energy of motion or position. This type of energy describes objects that are moving or could move. A moving ball can have energy from motion. An arrow can also have the energy of motion. Both are types of mechanical energy. Can you think of some other examples? Where does the energy of motion come from? It comes from the energy created by position. This energy is stored energy. This means it is not moving yet, but it has the potential to move. How can you store energy? The arrow gains energy from the drawn bow. As the arrow is released, the bow releases its stored energy and puts the arrow into motion. Can you think of some other ways to store energy using position?
What question would one ask from this paragraph?
Answer: How is energy stored in a bow and arrow?

Imagine a glass of your favorite drink that never became empty. Now think about what really happens. You take a drink and there is less in the glass. You keep drinking and soon it is all gone. Good thing you have more to refill your glass. What if there would never be any more of your favorite drink. What would you do? Now you know the difference between renewable and non-renewable. Its too bad that many things here on Earth will run out. This includes some of our natural resources we depend on. Things like oil will not last forever. There is a limited supply. Someday, we will run out, so then what? At current rates of use, coal will last about 300 years. Petroleum will be used up in just a few decades.
What question would one ask from this paragraph?
Answer:
What will happen to oil and why?