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# Honors throwing ball in air

## on Oct 24, 2011

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## Honors throwing ball in airPresentation Transcript

• TERMINAL VELOCITY
• Going up?If an object is is thrown upwardaway from the surface of the earth(and we ignore air friction)…• As the ball is going up… • What happens to its velocity? What Its velocity decreases. Its direction does it act in? direction is upward • What happens to acceleration due to It is 9.81 m/s2. It is acting gravity? What direction does it act in? downward• What is its velocity at the maximum 0 m/s! height?
• Going up?If an object is thrown upwardaway from the surface of theearth (and we ignore airfriction)…• As the ball begins traveling down… Its velocity increases in the negative direction • What happens to its velocity? • What happens to its acceleration due to gravity? What direction It remains at -9.81 m/s2. It does it act in? is acting downward.
• ACCELERATION DUE TO GRAVITY• Negative & positive signs are VERY important in vertical motion • MUST be consistent • G is negative • Vertical downward displacement away from origin is negative • Vertical upward displacement away from origin is positive
• EXAMPLE: BALL THROWN IN AIR• Karl Malone tosses a ball straight up in the air vertically with an initial velocity of 10.0 m/s. What is the maximum height the ball will reach (neglect air friction)?Xi = 0m Vf2 = Vi2 + 2a(xf-xi)Xf = ?Vi = 10.0 m/s 0 = 102 + 2(-9.81)(xf -0)Vf = 0 m/sa= -9.81 m/s2 -100 = -19.62(xf -0)t= xf = 5.10 m
• EXAMPLE: BALL THROWN IN AIR• Karl Malone tosses a ball straight up in the air vertically with an initial velocity of 10.0 m/s. This time, find the time it takes the ball to reach its maximum height (neglect air friction)Xi = 0m Vf = Vi+ atXf = 5.10 mVi = 10.0 m/s 0 = 10.0 + (-9.81)tVf = 0 m/sa= -9.81 m/s2 -10.0 = -9.81tt= t = 1.02 seconds
• EXAMPLE: BALL THROWN IN AIR• Karl Malone tosses a ball straight up in the air vertically with an initial velocity of 10.0 m/s. This time, find the final velocity of the ball, if Karl catches the ball at the same location he threw it(neglect air friction)Xi = 0m Vf2 = Vi2 + 2a(xf-xi) The velocity of anXf = 0 m object tossed inVi = 10.0 m/s Vf2 = 10.02 + 2(-9.81)(0-0) the air will haveVf = ? the same velocity Vf2 = 10.02 + 0 but in the oppositea = -9.81 m/s2 direction when itt= Vf = - 10.0 m/s returns to its original posiion!!
• EXAMPLE: BALL THROWN IN AIR• Karl Malone tosses a ball straight up in the air vertically with an initial velocity of 10.0 m/s. This time, find the time it takes the ball to reach its original position(neglect air friction)Xi = 0m vf = vi + atXf = 0mVi = 10.0 m/s -10.0 = 10.0 + (-9.81)tVf = -10.0 m/sa = -9.81 m/s2 -20.0 = -9.81tt= t = 2.04 s
• OUR DATA SO FAR…Notice any At t = 1.02 s v = 0 m/spatterns?v = 0 m/s At t = 0.00 s Vi = 10.0 m/s At t =2.04 s v = -10.0 m/s
• WHAT DOES THIS LOOK LIKE GRAPHICALLY?• Graph of an object thrown vertically upward Displacement vs. time Velocity vs. time Acceleration vs. time
• MEASURE YOUR REACTION TIME!• Reaction time affects your performance in a number of activities• Today you will determine your reaction time!1. Have a friend hold a meterstick vertically between the thumb and index finger of your open hand. Meter stick should be held so that the zro mark is between your fingers with 1 mark above it. Do not touch meter stick, let it fall freely. Your catching hand should be resting on a table2. Without warning, your friend will drop the meterstick so that it falls between your thumb and finger. Catch the meter stick as quickly as you can!3. Record the distance the meter stick falls through your grasp. Do this five times.4. Calculate your average reaction time from the free fall acceleration and the distance you measure.