Day 4 1-31-11 UNIT 5 Free Fall and 2D Motion Topic: Free Fall Objective: I will describe an object in free fall Science Starter: What is the velocity and the acceleration at the top of the arc?

Pre-test scores and graph Construct a bar graph in your notebook for pre and post test results. Enter your pretest score. Write down your extra points.

A ball thrown upward is also in free fall after it leaves your hand A ball thrown upward is also in free fall after it leaves your hand. Although you might not describe the ball as “falling,” it is still in free fall.

What would a V-t graph of a tossed ball look like? Slope of line is Acceleration due to gravity V Ball leaves hand g= -9.8m/s2 Pinnacle of throw Save bottom slope for from a drop slide 4 0r 6 t Freefall from a drop

Objects in free fall on Earth accelerate downward at 9.8 m/sec2, the An object is in Free Fall if it is accelerating due to the force of gravity and no other forces are acting on it. Objects in free fall on Earth accelerate downward at 9.8 m/sec2, the acceleration due to gravity.

The speed of a dropped object will increase by 9 The speed of a dropped object will increase by 9.8 m/sec every second (Figure 2.11). If it starts at rest, it will be moving at 9.8 m/sec after one second, 19.6 m/sec after two seconds, 29.4 m/sec after three seconds, and so on.

Note: Make average speed calculation first. (2-step process)

What is the average speed of a rock that falls for 5 seconds?

1. You drop a ball from the edge of a cliff. It lands 4 seconds later. a. Make a table showing the ball’s speed each second for 4 seconds. b. What is the ball’s average speed during the first second it is in free fall? c. What is the ball’s average speed for the whole 4 seconds? d. What distance does the ball fall during the 4 seconds?

Follow-up Questions 1) Describe the motion of an object in free fall. 2) Distinguish between mass and weight. 3) Explain how air resistance affects the motion of objects.