10'1 Kinematics and Kinetics

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Chap. 10 Introduction to Dynamics
10.1 Kinematics and Kinetics

• Dynamics the study of bodies in motion
• Kinematics
• Description of geometric and time-dependent
  aspects of motion without dealing with forces
  causing motion
• Position, velocity, acceleration
• Kinetics
• Newtons law of motion
• Energy method changes in velocity
• Momentum method impulse (impact and collision)
• Kinesiology
• study of human motion characteristics, including
  joint and muscle forces and neurological and
  factors

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10.2 Distance and Displacement
Quantities Scalar vs. Vector (1)
start
Displacement
Distance
finish
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10.3 Speed and Velocity
Quantities Scalar vs. Vector (2)
Unit LT-1 or (m/s)
Current velocity
Swimmers Velocity
Resultant Velocity
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10.4 Acceleration
Acceleration
Acceleration Change in Velocity / Change in Time
Unit LT-2 or (m/s2)
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Sample Problem
a -0.3 m/s2
v1 4 m/s
v2 0
t 0
t ?
Average and Instantaneous Quantities
Instantaneous quantities
average
time
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10.5 Inertia and Momentum
Inertia

• The tendency to maintain its state of motion
• Resistance
• Mass (m), Moment of inertia (I)

Momentum, P

• The tendency to resist changes in the existing
  state of motion
• P m v
• Only the moving object have momentum.
• Every object - stationary or moving - has
  inertia.

10.6 Degree of Freedom
Degree of Freedom (DOF)

• The ability to move in space
• Completely unrestrained object 6 DOF ( 3
  translational and 3 rotational)
• Human hip joint 3 DOF
• Human elbow joint 2 DOF