2. Speed & Velocity
• Speed - the rate of change in
position over time (distance/time)
• Instantaneous speed
• Average speed
• How is velocity different from
speed? Velocity describes both
speed and direction
6. Balanced Forces
Book on table
1. Weight of the book
is downward force
caused by gravity
2. Table pushes back
with an equal and
opposite force
Net force is zero
9. Types of Friction
• Static Friction: (Couch Potato)
–Force between objects at rest
• Sliding Friction: (Ice skating)
–Solid surfaces slide over each other
• Rolling Friction: (Rollerblading)
–An object rolls over a surface.
• Fluid friction: (Submarine)
–An object moves through a fluid
15. Newton’s 1st
Law
An object at rest remains at
rest and an object in motion
will continue moving at a
constant velocity unless acted
on by unbalanced forces.
19. Newton’s 2nd
Law
• More force means more
acceleration
• More mass means less
acceleration
Force = mass X acceleration
F = ma
20. Newton’s 3rd
Law
For every action, there is an equal
and opposite reaction.
Forces occur only in pairs
– Act on different objects
– Equal and opposite
21. Newton’s 3rd
Law
The hammer
exerts a force on
the nail to the
right.
The nail exerts an
equal but opposite
force on the
hammer to the
left.