1. Warmup
If dropped from the same height (discounting air resistance), which will hit the ground first: a bowling ball or a feather? Explain your answer.

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Feather and Coin

3. One Dimensional Motion
Free Fall
One Dimensional Motion

4. Objectives
To describe and analyze motion in one dimension including speed and velocity as they relate to free fall.

5. Δx = horizontal distance Δy= vertical distance a = -9.81 m/s2
Falling Objects
Δx = horizontal distance
Δy= vertical distance
a = m/s2

6. Gravity
Gravity on Earth accelerates everything at m/s2 toward the center of the Earth.
Assume no air resistance.

7. Displacement The ball’s speed is the same
at any point going up or down because
its acceleration is constant.
So...when you toss a ball up,
the distance between your hand
to the top and down to the
original point cancels out.

8. Displacement Problem:
If the initial velocity of a ball is 10.5 m/s when it is thrown upward from a height of 1.5 m, what is the velocity of the ball when it passes this point on the way down?

9. Graph On this velocity-time graph, the slope of the line (ball’s
acceleration) is constant.

10. Group Practice (Use your formula sheet)
A robot probe drops a camera off the rim of a 239 m high cliff on Mars, where the free-fall acceleration is -3.7 m/s2.
Find the velocity with which the camera hits the ground.
Find the time required for it to hit the ground.

11. Group Practice (Use your formula sheet)
A tennis ball is thrown vertically upward with an initial velocity of +8.0 m/s.
What will the ball’s speed be when it returns to the starting point?
How long will the ball take to reach its starting point?

12. Extra Information Skydiving:
If the Earth had no atmosphere, skydivers would accelerate with free-fall acceleration and splat on the ground. Because of air resistance on the parachutes, acceleration decreases as they fall, until it drops to zero. The speed then becomes constant. This is called terminal velocity.

13. Independent Practice

14. Objectives
To describe and analyze motion in one dimension including speed and velocity as they relate to free fall.

15. Reflection
If a coin is tossed upward, what happens to its velocity in the air?
Does the acceleration increase, decrease, or remain constant while it is in the air?