 Mechanics: The study of motion of objects ;]  Kinematics… WHAT IS THAT? › The science of describing the motion of objects  Measure by using graphs, diagrams, numbers, and equations  Scalars- quantities that are fully explained by magnitude alone  Vectors- quantities that are explained by magnitude and direction › THE SIGN MATTERS!

 The sign matters b/c it determines the direction of the object  Distance and displacement both show how an object moves › Distance is a scalar and shows the amount of distance covered › Displacement is a vector and shows the overall change in an objects position  Speed and velocity are both important to know in order to understand kinematics

 In some instances, you may not know a variable of an object’s motion and must solve for it! › A car has a velocity of 23 m/s East; and has an acceleration of 9 m/s2. What don’t we know? › Use the equations:

 Make a list of givens  Draw any helpful pictures  Identify what needs to be found  Jot what equation will be used  This will limit your chances of making error on your final =)  v= velocity; a=acceleration; t= time, =displacement

 Ima Hurryin is approaching a stoplight moving with a velocity of m/s. The light turns yellow, and Ima applies the brakes and skids to a stop. If Ima's acceleration is m/s 2, then determine the displacement of the car during the skidding process.  To prepare for solving we would make a list: › V i = m=/s › V f = O m/s › a= -8 m/s 2 › = ? Make note of negative and positive signs!

 Make a picture:  What equation should we use?

 Solve… › Equation: › Substitute in your knowns: = m

  List: › V i = 0 m/s › t= 4.10 s › a= 6 m/s 2 › d= ? Ben Rushin is waiting at a stoplight. When it finally turns green, Ben accelerated from rest at a rate of a 6.00 m/s 2 for a time of 4.10 seconds. Determine the displacement of Ben's car during this time period.

 Picture:  Equation:  Work/Answer: = m

 Falling under the sole influence of gravity  Downward acceleration of 9.8 m/s/s  The motion of an object in free fall can be described by kinematics equations  If an object is dropped from an elevated height its initial velocity is zero  If an object is projected upwards in a vertical direction it will slow down as it rises. When its peak is reached the velocity is 0 m/s.  If an object is projected upwards in a vertical direction the velocity at which its projected is equal in magnitude and opposite in direction to the velocity it has when it returns to the original height

 Luke Autbeloe drops a pile of roof shingles from the top of a roof located 8.52 meters above the ground. Determine the time required for the shingles to reach the ground.  To prepare for solving we would make a list: › V i = 0 m=/s › d = m › a= -9.8 m/s 2 › t= ?

 Make a picture:  What equation should we use?

 Solve… › Equation: › Substitute in your knowns: 22  m = (0 m/s)*(t) + 0.5*(-9.8 m/s 2 )*(t) 2 › Solution:  t= 1.32 s

 A race car accelerates uniformly from 18.5 m/s to 46.1 m/s in 2.47 seconds. Determine the acceleration of the car and the distance traveled.  To prepare for solving we would make a list: › V i = 18.5 m=/s › V f = 46.1 m/s › t= 2.47 s › d= ? › a= ?

a = (delta v)/t a = (46.1 m/s m/s)/(2.47 s) 2 a = 11.2 m/s 2 2 d = vi*t + 0.5*a*t d = (18.5 m/s)*(2.47 s)+ 0.5*(11.2 m/s 2 )*(2.47 s) 2 d = 45.7 m m d = 79.8 m