Free Fall 9/24

Free Fall 9/24

Open Ended

Journal - Chop Wood Carry Water

Velocity-Time Graph

What would the velocity-time graph of the ball look like if it was moving upward with an initial velocity of 20 m/s and upward set as the positive direction?

Position-Time Graph

How about a position-time graph in the same scenario.?

Maximum Height

How do you determine the maximum height by looking at the position-time graph?

What about the acceleration?

Yes, hopefully you know by now that on earth the acceleration due to gravity is 9.8m/s^{2, but how can we determine it with a velocity-time graph?}

Open Ended

What is the acceleration of the ball at the maximum height?

Free Fall Rides

Amusement parks use the concept of acceleration to design rides that give the sensation of freefall. They usually consist of three parts, the ride to the top, momentary suspension, and the fall down!

Free Fall Rides

Motors provide the force needed to move the cars to the top of the ride. When the cars are in free fall, the most massive rider and the least massive rider will have the same acceleration

Free Fall Rides

Suppose a ride starts from the top at rest and i s in free fall for 15 s. What would be it's velocity at at the end of 1.5s?

Free Fall Rides

Choose a coordinate system with the positive upward and the origin at the initial position of the car. Because the the car starts at rest, v_i would be equal to 0.0 m/s. To calculate the final velocity use the equation for velocity with a constant acceleration. v_f=v_i + at_f

Free Fall Rides

How far do people on the ride fall during the 1.5s? Use the equation for displacement when the time and constant acceleration are known. x_f=x_i + v_it_f + (1/2)at_f²

Variations in Free Fall

When David Scott performed his experiment on the Moon, the hammer and the feather did not fall with an acceleration of 9.8 m/s². The value of 9.8 m/s² is free-fall acceleration only near the Earth's surface. The magnitude of free-fall acceleration on the Moon is about 1.6 m/s².

Variations in Free Fall

When we study force and motion, we will learn about factors that affect the value of free-fall acceleration. One factor is the mass of the object, such at the Earth or the Moon, that is responsible for acceleration. Free-fall acceleration is not as great near the Moon as near Earth because the moon has much less mass.

Variation in Free Fall

Free-fall acceleration also depends on the distance from the object responsible for it. This means that on Earth, at different altitudes, free-fall accleration can change. These variations are very small. For example, in New York City, the free-fall acceleration is about 9.81 m/s², and in Denver it is about 9.79 m/s².

The Vomit Comet

Oops, we don't have time. We will look at it tomorrow before the lab!

Open Ended

Exit Ticket - What 2 factors affect free-fall acceleration?