1. Your teacher has given you the following assignment:Your teacher has given you the following assignment:
Investigate the impact on plant growth of adding variousInvestigate the impact on plant growth of adding various
amounts of fertilizer to potted plants. Think about what youamounts of fertilizer to potted plants. Think about what you
would need to do to be certain that the fertilizer was having anwould need to do to be certain that the fertilizer was having an
impact on plant growth.impact on plant growth.
1. Which of the following would NOT be part of your1. Which of the following would NOT be part of your
experiment?experiment?
A.A.Use some new plant seeds and some old plants that have beenUse some new plant seeds and some old plants that have been
growing for months.growing for months.
B.B.Give each plant the same amount of water.Give each plant the same amount of water.
C.C.Keep all plants in a similar location.Keep all plants in a similar location.
D.D.Carefully note amounts of fertilizer each plant is given.Carefully note amounts of fertilizer each plant is given.
E.E.Have one plant receive the recommended amount of fertilizer.Have one plant receive the recommended amount of fertilizer.

2. ReviewReview
 Scientific MethodScientific Method
 VariablesVariables
 ConstantsConstants
 ControlControl

3. ForceForce
Force is a push or aForce is a push or a
pullpull
Can push or pull inCan push or pull in
any or all directionsany or all directions

4. ForceForce
 Metric unit – newtonMetric unit – newton
(N)(N)
 1 N = .22 lbs1 N = .22 lbs

5. ForceForce
The effect of a forceThe effect of a force
depends on two things:depends on two things:
Magnitude (strength)Magnitude (strength)
and directionand direction
Vector quantityVector quantity

6. FrictionFriction
 A force that acts toA force that acts to
prevent slippingprevent slipping
between twobetween two
surfacessurfaces

7. FrictionFriction
 Static friction- theStatic friction- the
frictional force needed tofrictional force needed to
be overcome to get anbe overcome to get an
object movingobject moving

8. FrictionFriction
 Kinetic friction- theKinetic friction- the
friction of an object infriction of an object in
motionmotion
 Kinetic friction isKinetic friction is
always less than staticalways less than static
frictionfriction