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Objectives
Lesson 2: Acceleration
Before we get into Newton’s Remember back when we talked
Second Law, we need to get up to about gravity? We learned that
speed with acceleration. In physics gravity accelerates things at 32
acceleration is defined as a feet per secondM. Now this may
change in velocity. In other make a little more sense. Gravity
words, it is a change in speed or a made something continue to
change in direction. It is how much increase in speed so that after one
time it takes something to go from second of having the force of
one velocity to another. gravity pull on something, that
something has reached a speed of
Remember that velocity is speed 32 feet per second. When that
and direction. If you go straight thing started falling it was at 0
ahead on your bike at a constant velocity, after a second it’s at 32
speed of 5 mph you are not feet per second after 2 seconds it’s
accelerating. Neither your speed at 64 feet per second and so on.
nor your direction is changing.
Now, if you are stopped at a stop It’s the old formula v = gt or
light and it turns green, you are velocity equals the gravitational
accelerating as your speed constant (32 ft/sM) times time. If
increases from 0 mph to 10 mph. something has an acceleration of 5
The same thing happens if you are ft/sM how fast will it be going after
traveling at a nice even 10 mph 1 second…2 second…3 seconds?
and slow to a stop. After one second it will be going 5
ft/s; after two seconds 10 ft/s; and
In physics we don’t use the word after three seconds 15 ft/s. Again,
deceleration. We use positive and it’s just like v = gt (v is velocity, g
negative acceleration. Now what is the gravitational constant, t is
happens if you are in a car and it time) but put the rate of
turns a corner at a constant speed acceleration of the object in place
of 15 mph? Is it accelerating or of g to get the formula v = at or
not? Well, the speed is not velocity equals acceleration times
changing but its direction is, so it is time.
indeed accelerating.
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