Transcript The Nature of Force and Motion

The Nature of Force and Motion
1. Force – A push or a pull – How strong it is and in
what direction?
2. Net Force – The sum of all forces acting on an
object.
3. Unbalanced Forces – can cause an object to
start moving, stop moving, or change direction.
An Unbalanced Force will cause an object to
Accelerate (A Net Force > 0).
4. Equal forces – Forces equal in strength, acting in
opposite directions. Balanced Forces acting on
an object will NOT change the object’s motion
(Net Force = 0).
The Nature of Force and Motion
5. Inertia – The tendency of an object to resist
change in its motion.
6. Mass – The amount of matter in a n object. The
SI or metric units used for mass will be the
kilogram (kg) or gram (g).
7. Newton’s 1st law of Motion – An object at rest will
remain at rest and an object that is moving at
constant velocity will continue moving at
constant velocity unless acted upon by an
unbalanced force.
8. Velocity – Speed in a given direction.
Distance / Time in a given direction
The Nature of Force and Motion
9. Acceleration – The rate at which velocity
changes over time.
Acceleration due to gravity = 9.8m / s 2
10. Speed – Distance covered per unit time –
Distance / Time
11. Momentum – Depends on the mass and
velocity of an object –
Momentum (Kg.m/s) = Mass (kg) x Velocity (m/s)
The Nature of Force and Motion
12. Newton’s 2nd Law of Motion – The net force of
an object is equal to the product of its mass
and its acceleration.
Force [N] = Mass [kg] x Acceleration [m/s2]
F = ma
13. Newton – 1 Newton [N] = 1kg x 1 m/s2
One Newton is the force required to accelerate a
1 kg mass 1 m/s2.
The Nature of Force and Motion
14. Friction – The force that one surface exerts on
another when the two surfaces move against
each other. Ex. Air Resistance
15. The Nature of Friction – Friction opposes
motion. Eventually friction will cause an object
to come to a stop.
16. The Strength of Friction – Depends on two
things, the types of surfaces involved and how
hard the surfaces come into contact with each
other. Friction can be both useful and harmful.
The Nature of Force and Motion
17. Sliding Friction – Two solid surfaces sliding
over each other. Ex. sled over snow
18. Rolling Friction – When an object rolls over a
surface. Ex. Bowling ball rolls down the lane
19. Fluid Friction – The friction that occurs when
an object moves through a fluid. Ex. The oil in
a car engine
The Nature of Force and Motion
20. Gravity – The force that pulls objects toward
the Earth.
Gravity = 9.8 m/s/s =9.8 m/s2
21. Free Fall – When the only force acting on an
object is gravity the object is said to be in free
fall. Fall for 10 seconds – Velocity of 98m/s
The Nature of Force and Motion
22. Projectile Motion – A ball that is thrown horizontally
from a certain height hits the ground at the same time
as a ball dropped from the same height.
The Nature of Force and Motion
23. Air Resistance & Terminal Velocity – When the
fluid friction from the air resistance equals the
force of gravity acting on the object, the object
has reached terminal velocity. This is the
greatest velocity the object can obtain.
24. Weight – The measure of the force of gravity
acting on the mass of an object.
Weight (N) = Mass (kg) x (9.8 m/s2)
25. Universal Gravitation – The force of gravity
acts between all objects in the universe.
The Nature of Force and Motion
26. Newton’s 3rd Law of Motion – If one object
exerts a force on another object, then the 2nd
object exerts a force of equal strength in the
opposite direction on the 1st object.
27. Newton’s 3rd Law of Motion - For every action
force there is an equal in strength and
opposite in direction reaction force. Ex. A ball
hits the wall and bounces back.
28. Momentum – The momentum of an object is
equal to the product of the object’s mass and
its velocity.
Momentum [kg.m/s] = mass [kg] x velocity [m/s]
The Nature of Force and Motion
29. Rockets – The rocket can rise into the air
because the gases they expel with a
downward force exert an equal but opposite
force on the rocket.
30. Satellites – An object that travels around
another object in space. – Always
Accelerating!
31. Centripetal Force – Any force that causes an
object to move in a circle.
The Nature of Force and Motion
32. The Law of Conservation of Momentum – The
total momentum of any group of objects
remains the same unless outside forces act
on the objects.