Journal Entry 12/14

The bus is accelerating at +1 m/s2, which means that its velocity (change in position over a time interval) is increasing by +1 m every second. I know this because I know that acceleration is the change in velocity over a time interval.

If the bus accelerates from the intersection at +1 m/s2, it will be 15 m from the intersection after 5.0 seconds. I know this because due to the acceleration, the change in the velocity is increasing by 1 m each second. Over the first second, the bus moves 1 m. Then over the second second, the bus moves 2 m. Over the third second, the bus moves 3 m. This continues for 5 seconds. These distances add up to 15 m.

Journal Entry 11/22

"Constant velocity" is a term that depicts an unvarying change in the distance an object moves each second. "Constant acceleration" is a term that depicts an unvarying change in the distance an object moves each second over a time interval. As I previously stated, the unvarying change in the distance an object moves each second is its velocity, so constant acceleration is the change in velocity per second. When driving, constant velocity and constant acceleration can be seen. If I drive down a dirt road for 15 miles for one hour, that would be an example of constant velocity because each minute I am traveling 0.25 miles. If I drive down the same dirt road for 15 miles, but travel 0.25 miles in the first minute, 0.50 miles in the second minute, and 0.75 miles in the

third minute, this would be an example of constant acceleration because the velocity is changing constantly over time.

An object cannot have a constant velocity and a constant acceleration because acceleration only occurs when there is a change in velocity.

Car B will reach the end of the 100 m drag strip before Car A. Car B moves a farther distance between each pair of consecutive seconds because its velocity is increasing over those seconds (and velocity is the change in distance over time). If Car B has a constant acceleration of 10 m/s^2, that means that between seconds 0 and 1, it moves 10 m and then between seconds 1 and 2, it moves 20 m. Car A only has a constant velocity which means that it is moving 10 m per second.

Journal Entry 11/30 Continued

Positive and Negative Velocity are determined based on the coordinate system used to describe the movement of an object. If a number line is used, and a ball starts at zero, then movement to the right would be considered to have a positive velocity, while movement to the left would be considered to have a negative velocity. Now if the number line was flipped over with the positive numbers on the left side and the negative numbers on the right side, the balls movement to the the right would still have a positive velocity, while movement to the left would still have a negative velocity. When you decide that movement in one direction is positive, then movement in the opposite direction is negative.

Journal Entry 11/30

1. If an object is said to be moving in one dimension, its position can be determined by one coordinate system (aka a ruler).

2. Because motion is determined in terms of velocity (which takes into consideration the distance traveled and the speed of travel), a change can occur depending on the coordinate axis used to describe it. Practice Page 26 shows this. In coordinate axis A, the car starts at -100 m and moves to 0 m. In coordinate axis C, the car starts at 200 m and moves to 100 m. Although the speeds for both axis are 50, the velocities are 50 m/s and -50 m/s respectively. The cars may be covering the same number of meters, but they are moving in different directions.

3. When an object has a positive velocity, and is in one dimension, it is moving to the right. When an object has a negative velocity, and is in one dimension, it is moving to the left.