Acceleration
• Objectives
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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 2nd Law F = m a
Acceleration
According to Newton’s 2nd Law
a=F/m
Force = Mass x Acceleration
Acceleration
Acceleration is
proportional to the Force
Force
Acceleration
Acceleration is
inversely proportional to the mass
Mass
Smart Pulley System
The Smart Pulley allows us to make measurements of
displacement (Dd) and time (Dt). By plotting velocity (Dd/Dt)
of a laboratory cart, acceleration can be experimentally
determined with a motion diagram.
mc
T
T
mwg
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)
Tension
m a = F
(M + m) a = m g
a = g m/(M+m)
g ~ 10 m/s2
Constant Velocity Motion
Displacement
SLOPE = velocity
Time
Velocity
Velocity is constant
Time
Constant Acceleration?
• With constant non-zero acceleration…
 Velocity versus Time is linear.
 Velocity changes uniformly.
 Change in Velocity (Dv) over change in time (Dt) is
average acceleration.
• Average acceleration = Dv/Dt
• What happens to Displacement?
Constant Acceleration Motion
Displacement
Time
Velocity
Slope = acceleration
Time