Lecture Notes

Falling Balls

Falling Balls:

Now we will examine the acceleration, velocity and position of a simple system

[Drop ball]

Acceleration ? = g = 9.8 m/s2 = constant

Velocity:

initial velocity = 0

speeds up

follows straight line toward Earth

Results:

• velocity keeps increasing with time
• would move even faster if I threw it down

Mathematically: velocity = initial velocity + acceleration x time

Note: velocity does NOT depend on mass

Position of falling ball:

[Drop balls from different heights]

Will the higher one ever catch up with the lower one ?

"catch up" = be at the same height at the same time

[Drop from same height - different times]

Will the early one ever catch up with the late one ?

[Drop from same height - different times - different initial velocity]

Will later one catch up now ? maybe

From these experiments and our observations:

position (height) at some time depends on:
• initial position
• initial velocity
• acceleration (often constant)
• time

Previous Lecture - - - INDEX OF LECTURES - - - Next Lecture