Chapter 2 : MOTION. p.16 in your book!. Aristotle (384-322 BC) Objects have a proper “place” And strive to get there. NATURAL MOTION - No force required ex: boulder “falls down” smoke “goes up” Thought heavier objects fall faster than lighter objects.
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Chapter 2 : MOTION
p.16 in your book!
Aristotle (384-322 BC)
Objects have a proper “place” And strive to get there.
ex: boulder “falls down”
smoke “goes up”
Thought heavier objects fall faster than lighter objects
UNNATURAL MOTION- Requires force
EX: push a book across table
“Leaning Tower of Pisa “ experiment
As a ball rolls down an incline it speeds up
Objects at rest tend to remain at rest.
Moving objects tend to remain moving.
EX: mph (mi/hr) , km/hr, cm/hr
/ = “per” = divided by ex: 100km/hr
Average speed= total distance covered
Av sp= Total distance covered = 100km =50km
time interval 2hrs hr
Trip could have variations in speed -average speed!
Av speed = Total distance covered
Av speed = 2.0km / 40 min
= 0.05 km /min
But… stopped for traffic,tied shoe,ran across the road… YOU GET THE IDEA!!
Velocity – includes speed & direction
ex: 60km/ hr North
This is a Vector Quantity- includes direction & magnitude.
What is the difference between constant speed & velocity?
V = D/T
D = V x T
T = D/V
V = velocity, D = distance, T=time
150 m in 15 secs
3km/hr • 1 hr
D = 3km
b. At this rate, how far in 2 hrs? 10 hrs?
3km/hr • 2 hr = 6km
3km/hr • 10 hr = 30km
But.. 30 km / s relative to the sun.
Newton’s 1st Law “THE LAW OF INERTIA”
“the table cloth trick”
“penny & index card inquiry”
Newton (N) – unit for force
An arrow represents Force as vector quantities.
Spring scale & block example on board
Attracted to the Earth with a force of __ N.
Weight of object (downward force)= tension in rope (upward force).
The block is at rest, so net force is Zero.
∑ - sum
Objects at rest have equal & opposite forces acting on them.
Support Force or “normal force”.- the upward force
EX: book on desk : weight & gravity
∑ F = 0
What is the net force on a bathroom scale when a 110 lb person stands on it?
A: Zero. Scale is at rest. Scale reads support force which has same magnitude as weight.
Equilibrium- state of no change.
An object moving at constant velocity is in dynamic equilibrium.