### Unit 3: Forces

In Unit 3, the class studied forces in depth- including the force of friction, gravitational force, and normal force. Gravitational force, also known as weight, is measured in Newtons and always pulls downward towards the Earth's surface. It can be found by multiplying a persons weight in kilograms by -10 m/s/s, which is the acceleration on Earth due to gravity. Friction is the force opposing motion between two surfaces that rub against each other. On a horizontal surface, friction works parallel to the ground. Normal force is the force that opposes gravitational force (on a horizontal surface). It pushes upward from the surface that holds the object; it is the force that keeps objects from falling through tables or the floor! When on a incline, normal force will no longer work opposite of the force of gravity- it will be angled like the plane it is on.
Perhaps the most important formula we used in Unit 3 was F = m*a. It is also the most simple. Another vital part of our unit was Newton's three laws. The first law states that an object in motion tends to stay in motion unless an outside force acts upon it. The same goes with an object at rest. Newton's second law simply tells us the relationship between force, mass, and acceleration: F=m*a. The third law concludes that for every action, there is an equal and opposite reaction. During our unit assessment, we focused on this law, as we dealt with the pushes off of walls and each other.

#### Unit 3 Progress Sheet Gustafson

For our Unit 3 assessment, we applied our knowledge of forces to a fun competition. Given three carts, the goal was to launch the third cart as far as possible after pushing off of the wall. My group, consisting of myself, Emily, and Kirsten, decided that our pushes would be the most effective if they were done at exactly the same time. In the end, Emily's cart traveled farther than any other!
Using the Explain Everything app, I then made a video that ultimately led to finding the acceleration of Emily's cart, 43.2 m/s/s. In it, I found the friction of her cart, and the net forces, or total forces, of all three.

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