Purpose

1. Purpose • Understand how and when objects accelerate. • Understand the nature of acceleration. • Understand the relationship of acceleration, velocity, and position versus time.

2. Acceleration: • Any time the velocity changes, an acceleration occurs. • The direction ofacceleration is the same as that of change of velocity. Be careful with this! For example, when a car applies its brakes, the velocity vector and acceleration vectors are in opposite directions.

3. Equipment • Carts with wheels rolling on tracks. • Motion sensors track position, velocity, and acceleration of carts versus time. • 4 different track configurations (do one of each) • Single flat track with one motion sensor • Single sloped track (put a wood block under one side of flat track) with one motion sensor. • Double track V-shaped with motion sensors at both ends • Double track, one track flat, the other sloped with motion sensors at both ends • Note for double tracks: • Two groups can work on a double track simultaneously • (analyzing cart motion from the two different sides). • Do not change the slopes of double tracks. Change to the other double track instead. • Motion sensors may need adjustment (see next slide).

4. Adjusting the motion sensor if needed (double track) • Make sure that cart can be detected properly by motion detector across the entire length of the track: • Hold cart at “other” (than motion sensor) end of the track. • Open Capstone activity “Changing Motion.ds”. Click “Record”. • Distance should read approximately 4m for double track for this position. • Gently push cart in direction of motion sensor. Does it track distance smoothly? • If tracking is poor, readjust motion sensor direction (Hint: it tends to track better if motion sensor is tilted slightly “upwards”).