1. Chapter-3 Falling Objects and Projectile Motion
Overview:
Explore how objects move under the influence of gravity close to the surface of the earth.
Outline:
Acceleration due to gravity
Falling object
Projectile motion

2. Falling Objects Why objects fall to the ground when released?
When you drop objects of different sizes and weights, do they reach the ground at the same time?
Measuring the acceleration due to gravity for Earth: 9.8 m/s2

3. Falling Object: Velocity and Distance

4. Spread Sheet (Excel) Calculations v=v0 + at d=v0t+1/2 at2
Reaction Time Experiment

5. Throwing up a ball: Velocity and Distance
Q: A ball is thrown straight upward and then returns to the Earth. Does the acceleration change during this motion?

6. Throwing up a ball: Velocity VS. Time graph

7. Example
Jason hits a volleyball so that it moves with an initial velocity of 6.0m/s straight upward. If the volleyball start from 2.0m above the floor, how long will it be in the air before it strikes the floor?

8. Given Vi= +6.0m/s a= -g= -9.81m/s2 Δy= -2.0m Δt= unknown Vf =unknown
First solve for Vf and use this to find Δ t
Vf2 =Vi2 + 2aΔy
= (36) + (2 (-9.8)(-2)
= 75.2
= (be careful with sign…. Its NEGATIVE downward
Vf =Vi + aΔt
= 6.0 +(-9.8)(Δt)
Δt = => 1.5s

9. Practice
Pg 60
#1 .. To be completed in class… before recess
#2 and 3 for homework.