Acceleration

1. The quantity that describes the rate of change of velocity in a given time interval is called acceleration. 2. A car going coasting from the top of a hill to the bottom of a hill; increasing speed by the time it reaches the bottom. Also, a roller coaster starting at 0 mph and picking up a 60 mph speed within a few seconds. 3. A change in velocity can be the same amount, but the times can be much different. For example, a car could go from 40 mi/h to 0 mi/h in about 5 or so seconds but if it needed to slam on the breaks quickly to avoid hitting something it could go from 40 mi/h to 0 mi/h much faster; maybe 2 seconds. 4. To find the rate at which velocity changes per time interval, you take the final position minus the initial position divided by the final time minus the initial time. 5. Units are meters per second squared. 6. If the stopping time of a shuttle bus was very short, a person on the bus would be thrusted forward. They could fall if they were standing up. 7. When the velocity in the poitive direction is increasing, the acceleration is positive. When the velocity is constant, the acceleration is 0. When the velocity in the positive direction is decreasing, the acceleration is negative. 8. Similar to the answer in number 7, the slope shows how the acceleration is going. if the slope is positive, then the object is accelerating. If the line is going down, then the acceleration is decreasing. 9. If an object has constant acceleration then its average acceleration is 0. 10. Displacement is the relationship between velocity and time. It depends on acceleration, initial velocity, and time. The equation to find displacement is time times velocity (d=tv). In the speed lab the displacement showed which direction the car was moving. If the displacement was negative that meant the car was moving towards you and if it was positive that meant the car was moving away from you. 11. For an object traveling with constant acceleration, the average velocity is equal to the average of the initial velocity and the final velocity. In the rolling ball lab, the velocity increases as the ball rolls farther down the ramp.

Freefall Acceleration: ** 1. How is the velocity changing every second? ** The velocity is speeding up for every second that it travels if the object is accelerating. If the object is slowing down, then the velocity will be decreasing with every second that it travels. For this graph, the object is traveling upwards, so it is slowing down for every second it moves. When it reaches the top of its travel, it begins to fall back down. It is accelerating every second as it falls, until it comes to a stop, where it is then at a velocity of 0 m/s. If you were falling for 1 second, you would be moving at about 20 miles per hour. This is because if you were looking at meters per second, it would be about 9.8. To get to miles per hour you just mutiply the number by two which gives you roughly 20 mph. **3. Does mass effect the rate at which velocity change for falling objects?** No, the mass does not effect it the rate at which velocity changes for a falling object. Due to the laws of gravity, every object will fall at the same pace. __**Up and Down Motion:**__ **1. What is the rate at which velocity changes through the entire motion?** You have an initial velocity that is higher than 0 so that the object can move up. as soon as it starts moving up, it begins to slow down. When the object reaches max height it stops for a short period of time and then begins to move back down. The object is accelerating as it comes back down, so the velocities are getting bigger. The initial and final velocities are the same, except initial is positive and final is negative. The object travels 32 ft/s/s or 9.8 m/s/s. Slope of the red line. It is found on the velocity versus time graph. The slope does not change and it is always at -9.8 m/s/s The starting speed is not 0. 5. What is the speed right before it hits the ground?**
 * 2. If you were falling for 1 second, how fast are you traveling in miles/hour? **
 * 2. Where is the rate of velocity change marked on the graph?**
 * 3. What is the starting speed?**
 * 4. What is the speed at max height?