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PhysAug17

PhysAug17 - August 17 August 17 Physics In In A truck...

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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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