Download Name: Chapter 2 Guided Notes P.S. Teacher: Price Motion and

Name: ______________________
Chapter 2 Guided Notes
P.S. Teacher: Price
Motion and Speed: Chapter 2
Section 1: Describing Motion
A. Motion
1. _______________ – change in ________________
2. Distance - how _________ something has moved
3. Displacement - distance and ____________________ from the starting point
4. If a football player runs 100yds in one direction and turns around and runs 70 yds back, the displacement is equal to
the difference.
100yds – 70 yds = ?
B. Speed
1. ___________________ – Distance / time
2. Rate - any _____________ over time
3. Calculation for speed:
speed = distance / time
4. _____________________ speed - speed that doesn’t change
5. Instantaneous speed- speed at a _____________________ point
S (meters/second)= d (meters)/ t (seconds
1. A car traveling at a constant speed covers a distance of 750m in 25s. What is the car’s speed?
D=750m
T=25s
S=“what we need to find”
What do we need to do to find the speed of the car?
C. Graphing Motion
1. The motion of an object over a period of time can be shown on a distance-___________ graph
2. Distance is plotted on the ____________ axis (y)
3.
4.
Time is plotted on the ___________________ axis (x)
The slope of a line gives the speed of an object in motion
D. Velocity
1. Velocity – speed and direction 5 m/s N
a. How are speed and velocity different?
b.
These 2 escalators have the same speed but why do they have different velocities?
Section 2: Acceleration
A. Acceleration
1. Acceleration - change in velocity’s rate
2. Positive acceleration - speed is increasing
3. Negative acceleration - speed is decreasing
4. When an object changes speed or direction, it is accelerating
B. Calculating Acceleration
1. ___________________= final velocity - initial velocity over time
a = v f – vi / t
2. Units of acceleration – m/s2
3. A speed/time graph tells you if the acceleration is positive or negative
• ______________ acceleration – “+” numbers with “+” slope on graph
• Negative acceleration –”-” numbers with __________ slope on a graph
Review Problems: Acceleration
1. A ball is dropped from a cliff and has an acceleration of 9.8m/s2. How long will it take the ball to reach a speed of
24.5m/s2?
2.
A sprinter leaves the starting blocks with an acceleration of 4.5m/s 2. What is the sprinter’s speed 2s later?
Discussion Question:
Most sports rely on the ability of people to make quick changes in acceleration.
-------------1). What is some of the equipment used in different sports to make acceleration easier?
Answer:
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Section 3: Motion and Forces
A. What is force?
1. ________________ – a push or a pull
2. Net force – when ______ or more forces combined act on an object at the same time
3. If the 2 forces cancel each other out, what do you think the net force will be?
B. Balanced vs. Unbalanced Forces
1. ________________________ Force – forces on an object that are equal in __________ and opposite in direction
The _________ force = 0
2. Unbalanced Force – forces on an object that are ___________________ in size and opposite in direction
The net force = the _________________ force
C. Inertia and Mass
1. __________________ – the tendency of an object to ________________ any change in its motion
2. The larger the _____________ of an object, the greater its inertia
3. _________________________ Laws of Motion – rules that describe the effects of forces on the ___________________ of objects
4. Newton’s 1st Law of Motion – an object moving at a ____________________ velocity keeps moving at that velocity unless an
unbalanced net force acts on it
D. What Happens in a Crash
The law of inertia (a.k.a. Newton’s 1st Law) can explain what happens in a car crash
Inertia causes this unrestrained crash test dummy to continue moving at the speed of the car before the crash
SEE PICTURE
Balanced or Unbalanced
Two students push on a box in the same direction, and another student pushes on the box in the opposite direction.
1. Is this force that is being exerted balanced or unbalanced?
2. What does the net force equal?