Here is a recap for some of our conversations from the past two weeks please read through carefully and see how much of it is sticking.
- Forces are responsible for all objects motion
- PAST FORCES cause object to move the way they are in the PRESENT
- CURRENT FORCES affect how the objects motion is changing in the PRESENT. We use Free Body Diagrams to determine how an objects motion is changing.
- If all the forces on an object are BALANCED then:
- the object is either not moving or
- moving at the same speed in the same direction
- if all the forces DO NOT BALANCE then the object must be ACCELERATING meaning either:
- speeding up or
- slowing down
- Putting 2 and 3 together one can fully define how an object's motion is changing at a specific moment in time. For example: a ball that has been thrown vertically up and is on its way back down is speeding up towards the ground because the force of gravity is acting in the same direction of motion (down).
- If all the forces DO NOT BALANCE then the object must be accelerating. The rate of the acceleration (how quickly an object speeds up or slows down) is dependent on two things:
- the size of the UNBALANCED FORCE - the bigger the force the more the object will speed up or slow down
- the MASS of the object - the larger the mass the slower the object will speed up or slow down
- ALL FORCES must exist as pairs that are equal in strength and in opposite directions (one acting on one object and the other on a second object). A singular force is not possible and has no meaning.
PLEASE read Through Section 3.2 (Newton's First Law), 3.3 (Newton's Second Law), and 3.4 (Newton's Third Law) from the textbook. Identify Newton's three laws of motion in our summary above. Write your own summary in your own words to consolidate our learning thus far using the proper terminology from the textbook.
If you have finished and feel confident try some of the practice problems from the textbook sections.
Have fun and keep thinking hard.
RZ
