Chapter 2 Motion in 1 -...
Transcript of Chapter 2 Motion in 1 -...
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September 17, 2013
Chapter 2Motion in 1 Dimension
2-1 Displacement and VelocityDisplacement
-Change in __________ of object
Δx = __________ -straight line from ______ to _______ position (shortest distance)-SI unit: __________ (m)-At rest object = 0m
Displacement = __________ -gives __________ and __________
Distance = __________ -gives __________
Displacement can be positive or negative-must choose a direction to be positive
-normally choose right or up to be +
Here we have a positive displacement taking place on the positive side of the axis. The start and finish are on the positive side of the axis, the starting position is smaller than the finish. Therefore, the displacement is __________ .
When the finish is closer to the origin and both are on the positive side of the axis then the displacement is negative. The arrow points to the left, the displacement is __________ and all is right with the world.
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Displacement towards the origin on the negative side of the axis is positive. Subtracting −4 from −1 gives a positive +3. The arrow points to the right so the sign is right.
Use the diagram to determine the resulting displacement and the distance traveled by the skier during these three minutes.
Displacement: √
(42 +32 ) = 5m NE
Distance: 4m + 3m = 7 m
3m
4m
Velocity - measures how __________ something moves between 2 points
-units = m/s or miles/hr or km/hr-v =__________ -v = __________ /__________ -vector
Speed - magnitude = __________ /time-scalar
During a race on level ground, Andra covers 825m in 137s while running due west. Find Andra's average velocity.Knowns:
Page 44, # 1-6
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Graphing VelocitySlope = __________ =velocity
v = Δx/Δyy = mx +b d=vt+di
Constant Velocity
Changing Velocity (acceleration)
How do you determine instantaneous speed (velocity) for the curved line?
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What is the velocity?The positiontime graph below represents the motion of South's basketball coach during the last sixteen seconds of overtime during this past weekend's game.
Use the graph to answer the next several questions.a. Determine the total distance walked by the coach during these 16 seconds.b. Determine the resulting displacement of the coach during these 16 seconds.c. Determine the displacement of the coach after 12.0 seconds.d. At what time did the coach have the greatest displacement from his starting position?e. What was the fastest speed which the coach walked during any of the time intervals for the last 16.0 seconds?f. What was the average speed of the coach for these 16.0 seconds?
a. What is the velocity for each stage of the journey?b. What is the average (mean) velocity for the whole journey?
Section review Page 47 # 1 6
2-2 Acceleration - Change in __________ /change in __________ a = Δv/Δt
-unit = __________ -__________ = magnitude and direction-If you run around a track at a constant speed, is there acceleration?
As a shuttle bus comes to a normal stop, it slows from 9 m/s to 0 m/s in 5 s. Find the average acceleration of the bus.
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PRACTICE 2B - page 49 # 1-5
Find the acceleration of an amusement park ride that falls from rest to a speed of 28 m/s in 3.0 s.
Find the time required for the following vehicles to reach 27 m/s from rest.a) a motorcycle with an average acceleration of 15 m/s2
b) a sports car with an average acceleration of 5.2 m/s2
c) a dump truck with an average acceleration of .8 m/s2
Acceleration Confusing Points~ :)1) Acceleration in physics can mean speed up or slow down2) Changing direction is acceleration3)Negative acceleration normally is slowing down but can be speeding up
-if you are traveling away from the origin with increasing velocity but in the negative direction ACCELERATION IS NEGATIVE-+ velocity (but slowing down) and + direction (1st quadrant) = - acceleration- - velocity (speeding up in - velocity quadrant) and -
direction (4th quadrant) = - acceleration4)Positive acceleration normally is speeding up but can be slowing down-if you are traveling to the origin in the 4th quadrant and slowing down, ACCELERATION Is POSITIVE-+ velocity (speedin up) and + direction = + acceleration- - velocity (slowing down in - v quadrant) and - direction
= + acceleration
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Motion with a Constant Acceleration velocity increases by exactly same amount during each time interval
Δv = vf vi vavg = (vi + vf)/2vavg = displacement/time of Δx/Δt
d= 1/2(vi + vf)Δt
A racing car reaches a speed of 42 m/s. It then begins a uniform negative acceleration, using its parachute and braking system, and comes to rest 5.5 s later. Find how far the car moves while stopping.
A bicyclist accelerates from 5 m/s to a velocity of 16 m/s in 8 s. Assuming constant acceleration, what distance does the bicyclist travel during this time interval?
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While a baseball is being hit, its speed changes from 35 m/s to +52 m/s in a time interval of .10 s. Assuming constant acceleration, what is the ball's displacement during this time interval?
Practice 2C page 53 # 15
vf = vi + aΔt
d=viΔt + 1/2(a)(Δt)2
d= 1/2(vi + vf)Δt
A plane starting at rest at one end of a runway undergoes a constant acceleration of 4.8m/s2 for 15 s before takeoff. What is its speed at takeoff? How long must the runway be for the plane to be able to take off?
A car can finish a 4.0 x 102 m race in 6.0 s. What is the minimum constant acceleration necessary?
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A car on a wet road can achieve an acceleration of only 10m/s2 without sliding. Find the required stopping distance for a speed of 48 km/h (30 mi/h).
Practice 2D # 14 page 55
Did you know?
physics Ancient Greek word for "nature." Aristotle believed motion was the basis of physics. However, he thought math could not be applied to this study.
Galileo disagreed. He developed the foundation for studying motion through math.
vf = vi + aΔt
d=viΔt + 1/2(a)(Δt)2
d= 1/2(vi + vf)Δt
vf2 = vi2 +2aΔd
A baby sitter pushing a stroller starts from rest and accelerates at a rate of .500 m/s2. What is the velocity of the stroller after it has traveled 4.75 m?
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An aircraft has a landing speed of 302 km/h. The landing area of an aircraft carrier is 195 m long. What is the minimum constant acceleration required for a safe landing?
An electron is accelerated from rest in an accelerator at 4.5 x 107 m/s2 over a distance of 95 km. Assuming constant acceleration, what is the final velocity of the electron?
Practice 2E # 15 page 58
Section 23 Falling Objects Free Fall (g)
Constant a of 9.8 m/s2This book declares negative as the downward direction so things accelerating towards earth (free fall) actually have an acceleration of 9.8 m/s2
apple and feather fall at same rateair resistance affects free fall
What is the velocity and total distance covered by the graphic?
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What goes up must come downwhen a ball is thrown in the air, it has a downward (negative acceleration)when the ball returns to the ground, it speeds up (still negative acceleration)when the ball reaches the highest position, it is motionless with zero velocity BUT acceleration is sti 9.8m/s2
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Quick Lab page 62 need meter stick or
ruler
Jason hits a volleyball so that it moves with an initial velocity of 6 m/s straight upward. If the volleyball starts from 2 m above the floor, how long with it be in the air before it strikes the floor? Assume that Jason is the last player to touch the ball before it hits the floor.
Practice 2F #16, Page 64