Acceleration Objectives –Make simple measurements of distance and time –Learn graphing skills and understand graphical relationships –Understand the meaning and use of the slope in a motion diagram –Study acceleration and its dependence upon mass and force. –Understand Applications of Newton’s 2 nd Law F = m a

Acceleration According to Newton’s 2 nd Law Force = Mass x Acceleration a = F / m Acceleration is proportional to the Force Acceleration is inversely proportional to the mass Acceleration Force Acceleration Mass

Smart Pulley System The Smart Pulley allows us to make measurements of displacement (  d) and time (  t). By plotting velocity (  d/  t) of a laboratory cart, acceleration can be experimentally determined with a motion diagram.

Forces Forces on cart M (ignoring friction) Normal Force (from table) Gravity (weight) Tension (from hanging mass weight) Forces on hanging mass (m) Gravity (weight) m a = F Tension(M + m) a = m g a = g m/(M+m) g ~ 10 m/s 2

Constant Velocity Motion Displacement Time SLOPE = velocity Velocity Time Velocity is constant

Constant Acceleration? With constant non-zero acceleration…  Velocity versus Time is linear.  Velocity changes uniformly.  Change in Velocity (  v) over change in time (  t) is average acceleration. Average acceleration =  v/  t What happens to Displacement?

Constant Acceleration Motion Displacement Time Velocity Time Slope = acceleration