1. Any push or pull -can cause change in motion:
a. friction b. inertia c. burn d. force
2. A force that always works against motion
a. friction b. gravity c. inertia d. momentum
3. What is the mass of a female Sumo Wrestler
that weighs 750N? Fg=mg
a. 7,350kg b. 76.5kg c. 765g d. 73.5g
4. If there is no net force on an object, it will
a. not change motion b. change motion c. move
NOW IT’S TIME FOR NEWTON’S 2ND
LAW
Newton’s 1st: Inertia. At rest, stay at
rest; in motion, stay in motion.
Newton’s 2nd: What happens when a
force acts on an object?
Acceleration.
NEWTON’S SECOND LAW:
The acceleration of an object is
directly proportional to the force
applied to the object, and inversely
proportional to the mass.
-or –
The net force on an object is equal to
the mass of the object multiplied by
its acceleration.
- or –
Newton’s Second Law:
Force = mass x acceleration
Force equals mass times acceleration.
F=ma
CALCULATE THE FORCE HOW DO WE?
HOW? LIKE THIS:
My 4 kg cat, Jeter, ran at our new kitten with
an acceleration of 3.0 m/s2. He didn’t stop.
Poor little kitten! After suffering a mild
concussion, we wondered….how much
force did Jeter hit him with?
Force = mass x acceleration, or…
4 x 3 = 12
12 WHAT?
Remember Force has its own special
unit…
1kg x 1m/s2 = 1 newton (1N)
F = ma
Learn it. Live it. Love it.
FORCE = MASS(ACCELERATION)
1. How much force is needed to move
a mass of 40 kg at 1.5 m/s2?
2. What is the mass of a rock that has
an acceleration of 2.3 m/s2 after a
force of 2300 Newtons has hit it?
3. How much force must be applied
to a toy car that has a mass of .25kg
to achieve an acceleration of
2.4m/s2?
4. What is the acceleration of a dog
with a mass of 15kg that hits with a
force of 300 Netwons?
TERMINAL VELOCITY……
Terminal Velocity- object will reach a speed
where the force of the drag will become
equal the force of gravity