Unit 2 blog post

Unit 2: Forces

Types of Forces

Gravity: Always goes down, vertical towards the center of the earth.

Push force: when an external force is pushing the object

Normal Force: always perpendicular to the surface.

Tension: Always along a rope.

Spring Force: when an object is pushed or pulled and in immediatly returns to its original state.

Force of Drag: also known as air resistance is the ammount of push an object going at high velocities  recieves from the air.

Friction: Parallel to the surface, oposing motion. NOT AFFECTED BY SURFACE AREA

Newton's first Law.

Newton had three laws of motion. His first law was demonstrated in the first class period that we went over this unit,  we used the gym floor as the our physics lab, we used a hovercraft to show how after an object was pushed if no other forces were applied it would not stop, at first this was a really big misunderstanding because the hovercraft was moving so most people thought that there had to be a force pushing to it. After a lot of discussion, we learnt Newton's first law, which says: "All objects at rest will stay at rest and all objects in motion will stay in motion unless an external force is applied". The hovercraft case is a perfect example for this law because the hovercraft will stay at rest unless someone pushes on it, and this motion will continue unless the hovercraft is stopped.

Free Body Diagrams

After we talked about forces we introduced a concept of a picture that shows what forces are being applied to an object.

Above you see 4 drawings all you might see is arrows and shapes, but this describes the type of motion an object is in, or if its accelerating, decreasing speed or changing direction. When forces are balanced (Arrows on opposite directions are congruent) means that an object is at rest or at constant velocity. when forces are unbalanced (Arrows not congruent) it can mean one of three things, that the object is speeding up, slowing down or changing directions. at some point the axis of the diagrams will be slanted, this means that the surface were the object is placed is slanted.

Weight Vs. Mass

 mass is what we usually see when we when we usually think about weight but it is the ammount of mass an object or a human has. Weight is this mass affected by the force of gravity.

Newton's 3rd law

Newton's 3rd law says that all actions have an equal and opposite reaction, these are called action reaction pairs, for example:

In this picture the kid is pushing on the ball but the ball is also pushing the kid back.

Connection to real life

when a baseball is thrown up, after it is released, there is only one force acting on it, gravity, contrary to popular beliefs there are no forces pushing this ball forward, only pushing it down, and it is causing the ball to change direction, it is not going in a perfectly straight line but going down.