1. NEWTON’S 2nd LAW

2. Newton’s 2nd Law and Centripetal Force
-Newton’s 1st law stated:
An object at rest tends to ____________________________
an object in motion tends to __________________________
as long as the forces are balanced.
stay at rest
stay in motion
change
-If the forces are unbalanced, the motion of the object will ___________.
-Newton’s 2nd law states (part 1):
When an unbalanced force acts on an object, the object will ___________________ in the direction that the unbalanced force
points.
accelerate
-The greater the force on an object, the greater the________________.
-The larger the ________ of an object, the larger the force necessary for
acceleration.
acceleration
mass

3. mass acceleration 2 remember: 1N= 1kg m/s acceleration mass (N) (kg)
-Newton’s 2nd law states (part 2):
The strength of the force equals the _________ of the object
multiplied by the _______________ of the object.
Force = __________ x ___________________
F= x
mass
acceleration 2
remember: 1N= 1kg m/s F
acceleration
mass
(N)
(kg) m x a
(m/s ) 2 m a
Ex. A baseball player hits a 0.1 kilogram baseball to accelerate it at a
rate of 4000 meters per second squared. What is the force of the
player’s hit?
Ex. A stalled car has a mass of 1000 kilograms. It is pushed forward
with a force of 2000 newtons. At what rate does the car accelerate?
m = 0.1 kg
a = 4000 m/s2
0.1 kg x 4000 m/s2 =
F = m x a
= 400 kg x m/s2
or 400 N
a = F m
F = 2000N or 2000 kg x m/s kg x m/s2
m = kg kg =
= 2 m/s2

4. opposite friction pushes pulls circular velocity acceleration
Deceleration
-To decrease the velocity of an object, the force must be applied
in the direction _______________ of the motion. Often this force comes from ___________.
opposite
friction
Centripetal force
-This is the force that ___________ or ___________ on an
object into a ________________ path.
If you recall:
-If you change the direction of an object, you change its ________
-If you change the velocity of an object, you change its _________
pushes
pulls
circular
velocity
acceleration
-Therefore, an object traveling at a constant speed is accelerating when it is not traveling in a straight line. According to Newton’s 2nd law, since the object is accelerating an unbalanced force must be changing the direction of motion.

5. It is always trying to travel in a straight line B? C C? D?
It is always trying to travel in a straight line
perpendicular to the string
(tangent to the circle), but as
long as you are holding the string (applying a force)
it must change directions.
Which direction will the ball travel
after it is released?

6. gravity 1 accelerate 9.8 2 19.6 9.8 3 29.4 m/s air friction terminal
Falling Objects
-As objects fall towards the ground they pick up speed due to
the force of ______________.
-All objects ______________ toward the ground at the same
rate.
-On earth the acceleration of falling objects is ________m/s2.
-Falling objects will continue to accelerate until they reach the
ground unless they are acted upon by an opposing force to
balance out gravity. A force that commonly opposed the
acceleration of falling is __________________.
gravity 1
accelerate
9.8 2
19.6
9.8 3
29.4 m/s
air friction
-When a falling object stops accelerating, it has reached its
_______________ __________________.
-Ever object falling through air, if it is falling long enough, reaches a
terminal
velocity
terminal
velocity

7. - shape of the object (aerodynamics) -air thickness
-Factors that affect terminal velocities:
- shape of the object (aerodynamics)
-air thickness
-How does horizontal motion affect rate of fall?
(this arrow will be dropped
vetically from the same height
at the moment he shoots)
-they would hit the ground at the same time!