Unformatted text preview: August 17
August 17
Physics In:
In:
A truck speeds up from 10 m/s to 15 m/s in 3 seconds. What was the acceleration of the truck? College “Monday”
College “Monday” Objective:
Objective: To learn the equation for displacement with constant acceleration.
Success criteria
To be able to solve velocity and acceleration problems How to decipher a problem
How to decipher a problem
Variable Unit
Δd Meters Velocity m/s Acceleratio m/s2
n
Time
Seconds Key word
How far, how high
How fast
What acceleration
How long Key words
Key words At rest means V=0
Comes to a stop V2=0 From = first (initial velocity)
To = second (final velocity)
Accelerates at a rate of = acceleration Pull out the variables
Pull out the variables Make sure that you have the right numbers and units
Write down what you are looking for Choose the right equation
Choose the right equation Look at the variables you have
Look at what you are looking for
Find the equation that has all of these variables including the one you are looking for. Solve for the variable you Solve for the variable you are looking for Do the algebra on the equation with letters before you put in any numbers
Then plug in the numbers
Solve the equation Check your answer
Check your answer Is it reasonable? – slowing down acceleration is negative
– speeding up acceleration is positive
– Positive acceleration V2 greater than V1
– Negative acceleration V2 less than V1
– Time is always positive Check back of book, friend, teacher Velocity and displacement Velocity and displacement with constant acceleration
Equations:
Velocity with constant acceleration: V2=V1 + at Displacement: Δd=V1t + ½ at2
Δd= ½ (V1+V2)t Problem Problem Velocity and displacement with constant acceleration A car with an initial speed of 4 m/s accelerates at a uniform rate of 1 m/s2 for 5 s. Find the final speed and the displacement of the car during this time. A driver of a car traveling a 15 m/s slows down with an acceleration of 2 m/s2. How long does it take the car to get to a final speed of 10 m/s? How far has the car moved during this time? A plane starting a rest at one end of a A plane starting a rest at one end of a runway undergoes a uniform acceleration of 4.8 m/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? Problem set: Motion
Problem set: Motion Work in pairs (that means two only)
One paper per pair Out:
Out: What is still confusing to you about motion problems? ...
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 Fall '11
 Burgeson
 Acceleration, Velocity

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