Acceleration

Acceleration

1. Acceleration- the rate of change of velocity with respect to time. 2. Examples: Bullet trains, speeding up from a stop and slowing down from top speed to pick up passengers. A shuttle bus speeding up after picking up passengers.

3. Change in Velocity- time final minus time initial

4. Finding the rate at which velocity changes per time interval- average acceleration=change in velocity/time required for change

5. Units of acceleration- meters per second per second =m/s/s

6. A person would feel the difference in the time interval before stopping between the bullet train and the shuttle bus. The bullet train had a gradual deceleration while the shuttle bus had a more abrupt stop. The different lengths of time intervals could be felt by the passengers. The stopping in the shuttle bus would be more uncomfortable because they would be thrown forward at a greater speed.

7. Positive acceleration occurs when an object speeds up from a positive velocity, or when an object traveling at negative velocity slows down. If the object is speeding up, then the acceleration is positive. If the object is slowing down, the acceleration is negative. Negative acceleration occurs when an object traveling at positive acceleration is slowing down, or when an object traveling at negative velocity speeds up.

8. For an object moving at constant acceleration, the average velocity is equal to the average of the initial velocity and the final velocity. It is determined by initial velocity added to final velocity, then divided by two.

9. There is no difference between average acceleration and acceleration when an object moves at constant acceleration.

10. The displacement is increasing __f__or every equal time interval for an object that is accelerating. As the ball rolled down the ramp, it gained speed, while the acceleration remains constant. The equation for displacement with constant acceleration is displacement equals 1/2(initial velocity+final velocity)(time interval).

11. The velocity increases for every equal time interval for an object that is accelerating. As the ball rolled down the ramp, it gained speed.or velocity, keeping the acceleration constant. The equation for velocity with constant acceleration is final velocity equals initial velocity +(acceleration x time interval). The velocity for each time interval is increasing at the same amount every time. The acceleration can be viewed on the graph as the slope. Freefall Acceleration 1.Velocity is decreasing every second as the object is going up, but the velocity increases as the object comes back down to where it was thrown. The direction of the velocity just depends on which way the object is traveling, positive velocity-going up, and negative velocity- coming down.The magnitude of the velocity can be seen on the velocity vs. time graph.

2. After falling for 1 second, the object is traveling at roughly 20 miles per hour. This is determined because the slope of the velocity vs. time graph is roughly 9.8 m/s and multiplying that number by two converts m/s to miles per hour, so roughly 20 mph.

3, Mass does not effect the rate at which velocity changes for freefalling objects. A heavier object will fall at the same rate as a lighter object.

Up and Down Motion Graph of Object that is going up and coming back down 1. The rate at which velocity changes throughout the entire motion is 9.8m/s per second. The acceleration is the same as the object goes up and then comes back down. 2. The acceleration is marked on the graph as the slope of the velocity vs. time graph ( the red line) or can also be seen on the acceleration vs. time graph ( the green line). The slope is negative 9.8 m/s/s. The slope never changes 3. The starting speed is 25 m/s, since it starts with velocity to get the object to go up against gravity. 4. The speed at max height is 0 m/s because it is switching direction. 5. The final velocity is the same as the initial velocity, just negative, based on which direction it is traveling.