The student will demonstrate an understanding of the effects of forces on the motion and stability of an object. Standard 8.P.2

Performance Indicator: 8.P.2A.1 Plan and conduct controlled scientific investigations to test how varying the amount of force or mass of an object affects the motion (speed and direction), shape, or orientation of an object. Performance Indicator: 8.P.2A.1

How varying the amount of force or mass of an object affects the motion (speed and direction), shape, or orientation of an object? THE QUESTION???

ANSWER BEFORE NOTES   ANSWER AFTER NOTES

SPEED FORCE MASS

SPEED A measure of how fast something moves a particular distance (ex. Meters, feet) over a certain amount of time (seconds, minutes, hour) (EX) Miles per hour Meters per second

Speed is the rate of change of the position of an object – or how far something will move in a given period of time   Distance-Time graphs represent the motion of an object away from a reference point

In a distance-time graph, TIME will always go on the X_-axis and will be the INDEPENDENT_ variable, whereas, _DISTANCE will always go on the _Y_-axis and will be the DEPENDENT variable. DISTANCE-TIME GRAPH

Misconceptions… Speed does not always mean something is moving “fast” or getting faster

FORCE Known as a push or pull of an object *Unit: Measured in _NEWTONS_(N) A force MUST be applied to an object to start it, stop it, change its direction, speed it up or slow it down

How FORCE affects motion and speed… If an object is in motion, and more force is applied, it will move faster If two objects have the same mass and a greater force is applied to one of the objects, the object which receives the greater force will change speeds more quickly. For example if a ball is hit harder, it will speed up faster. EX) a ball is hit harder, will speed up faster

How FORCE affects motion and speed… If an object must be slowed down quickly, the force applied to the object must be greater than if you wanted to slow it down gradually Changing or Varying the amount of force applied to a moving object can also change the direction of an object EX) a baseball pitched will quickly change direction if hit very hard …it will change more slowly if it is hit softly or bunted

Misconceptions… Force is not always applied by a human   Force is something that is not necessarily able to be seen EX) gravity, air resistance, and friction

MASS A measurement of how much matter is in an object Unit: Usually measured in kilogram (kg) or gram(g)

Mass and motion… If a heavy (more massive) object is in motion, more force must be applied to get the object moving faster. If the same force is applied to two objects (ex. Tennis ball, bowling ball), the one with smaller mass (tennis ball) will speed up more quickly

Mass and motion… In order to slow down or stop a heavier (more massive) object, the force on that object must be greater than for a less massive object. For example, if the same braking force is applied to a small car and a large truck, the car will slow down more quickly. Ex) A 18-wheeler truck will take more braking force to slow down than a compact car

Mass and motion… It is more difficult to change the direction of a heavy moving object, than one that is lighter in mass. Ex) Turning a full shopping cart vs. turning an empty shopping cart

Misconceptions… Mass is NOT the same thing as Weight   However, more massive objects will weigh more than less massive objects