Answer:
1.It is a force that occurs only on rough surfaces
2.C.
3.C.
4.A.
5.B.
6.A.
7.C.
8.B.
9.A.
10.A.
11.A.
12.Sandy Floor
13.A.
14.D.
15.C.
Explanation:
What is Friction? Friction is a force that restricts or stops the movement of two solid objects sliding along each other. The force of friction acts in the opposite direction of a moving object. When two or more objects rub against each other, they cause friction where they touch.
Gravity attracts all objects towards each other. Gravity has been around since the very beginning of the universe, and it works the same way everywhere in the universe, on all kinds of different objects, of all different sizes (larger than atoms – those are held together by atomic forces instead).
How much gravity an object has depends on how big it is (or to be specific, how much mass it has). It also depends on how close you are to the object; the closer you are, the stronger the gravity.
Gravity is very important to our everyday lives. Without Earth's gravity we would fly right off our planet! We'd all have to be strapped down all the time and if you kicked a ball, it would fly off forever. While it might be fun to try for a few minutes, we certainly couldn't live life on Earth without gravity.
Gravity also is important on a larger scale. It is the Sun's gravity that keeps the Earth in orbit around the Sun. Life on Earth needs the Sun's light and warmth to survive. Gravity helps the Earth to stay just the right distance from the Sun, so it's not too hot or too cold.
Nobody fully understands how gravity works, or even why gravity exists. One way of looking at gravity is to think of it not as a force like magnetism, but instead as a natural result of the way mass bends space. Any object with mass (like a star) pushes on space and bends it, so that other objects (like planets) that are moving in a straight line are also going around the star. It looks to us like the star is pulling on the planet, but really the star is bending space.
