NOTES 4:
F = ma (Newton’s 2 nd )
NEWTON’S 2nd LAW STATES…
The acceleration of an object is
dependent upon the force acting
upon the object and the mass of the
object.
F=ma
(force equals mass times acceleration)
MEASURING FORCE
4 types of measurement for Newton’s
2nd law:
•
•
•
•
ACCELERATION
m/s2
Newton
Mass vs. Weight
ACCELERATION
• The rate of change of the
speed or direction of a
moving object with respect
to time.
(AKA deceleration)
m/s2
• Unit used to express
accleration (a)
• meters per second per second
NEWTON (N)
• the SI (standard
international) unit for force
•Equal to:
•1 kg x 1m/s2
MASS vs. WEIGHT
MASS
The amount of matter in
an object
• MASS does not change – if I am
made up of 1 million atoms, I will
always be made up of 1 million
atoms. Even if…
WEIGHT
The vertical force
exerted by a mass as a
result of gravity
• WEIGHT is dependent on the
amount of gravity.
• Gravity is equal at all places
around the Earth, so we often use
weight as a shorthand to describe
the property of mass.
I weigh less on the Earth than I do on the moon even though my mass is the same.
OKAY, SO…
• F = ma
HOW DOES FORCE AFFECT ACCELERATION??
• The more force applied to an object, the more acceleration the object
will experience.
WHERE DOES MASS FIT IN?
• The greater the mass of an object, the less acceleration it will experience
under the same force
HOW DOES MASS EFFECT FORCE (the amount of
push/pull)?
•
The higher the mass of an object, the more force the object can apply.
EXAMPLE ONE
If I hit a baseball as hard as I
can, the ball accelerates more
than if I were trying to bunt
the ball.
WHY?
I’m applying MORE FORCE!!
EXAMPLE TWO
If I hit a baseball and a bowling
ball with the same force, the
bowling ball will go slower
than the baseball.
WHY?
The bowling ball has MORE
MASS and therefore
ACCELERATES LESS!!
EXAMPLE THREE
If I hit a baseball with a 24oz.
bat and a 32 oz. bat, the ball
will go farther with the 32 oz.
bat.
WHY?
The 32 oz. bat has MORE
MASS and can apply MORE
FORCE!!
Less acceleration (a) results in
less force (F)
F =ma
More acceleration (a) results in
more force (F)
F =ma
Less mass (m) results in less
force (F)
F =ma
More mass (m) results in more
force (F)
F =ma
Less acceleration (a) results in
more mass (m)
F =ma
More acceleration (a) results in
less mass (m)
F =ma