Physical Science

Review 3.1 (Gravity) 
Problem pg. 83 

6. Synthesize

 Presicion measurements of the acceleration due to gravity show that the acceleration is          slightly different in different locations on Earth. Explain why the force of gravity is not            exactly the same everywhere on  Earth's surface. Hint: Think about the details on Earth's      surface.

Answer:
Because of different elevations in Earth.

Review 3.2 (Friction) 
Problem pg.89

6. Synthesize

If you push a book against a wall hard enough, it will not slide down even though gravity is     pulling it. Use what you know about friction and newton's laws of motion to explain                   why the book does not fall.

 Answer:
It doesnt fall because you are pushing it to the wall and thewall is pushing it to you, in result are holding the object up so it doesnt fall.

Review 3.3 (Pressure)
Problem pg. 83

6. Synthesize

During cold winters, ice can form on small lakes and ponds.  Many people skates on thin ice and breaks  through it. Why do rescue workers lie flat on the ice instead of walking upright when reaching out to help rescue skater?

Answer:
Because the weight of the rescuer is divide in a bigger area and preasure is less because of this.