Motion - Acceleration – 11.3 1. The rate at which velocity changes is called ____acceleration____. 2. Acceleration can be described as changes in __speed____, changes in __direction ___, or changes in both. 3. Acceleration can be caused by positive ( _increasing______)change in speed or by negative (__decreasing_) change in speed. 4. ___Deceleration_______ is an acceleration that slows an object down. 5. Free fall is the movement of an object toward Earth solely because of __gravity____. The unit for velocity is meters/second. The unit for acceleration is meter/second/second. This measurement is written as ___m/s2_. 6. Objects falling near Earth’s surface accelerate downward at a rate of _9.8 m/s2__. 7. Acceleration can be the result of a change in direction at __constant____ speed. 8. Sometimes motion is characterized by changes in speed and __direction___ at the same time. 9. The velocity of an object moving in a straight line changes at a constant rate when the object is experiencing ___constant_____ acceleration. 10. How do you calculate acceleration? You divide the change in __velocity____ by the total time. Acceleration is the rate at which velocity changes. V1 is the __initial_____ velocity and Vf is the __final_____velocity and t is the total _time____. The means change. 11. If the velocity increases then the acceleration is __positive______. If the velocity decreases then the acceleration is ____negative___. 12. Acceleration and velocity are both vector quantities. This means they have both speed and direction. To determine a change in velocity, subtract one _velocity _ ___vector______ from another. 13. A ball roll downs a ramp, starting from rest. After 2 seconds its velocity is 6 meters per second. What is the acceleration of the ball? What information are you given? time = 2s starting velocity = 0 m/s ending velocity = 6 m/s What unknown are you try to find? acceleration Write the formula. Fill in the formula with what you know and solve. 6 m/s - 0 m/s = 3 m/s2 down the ramp 2s 14. The __slope____ of a speed-time graph is acceleration. ___Speed______goes on the vertical axis and __time___ goes on the horizontal axis. 15. Constant acceleration is represented by a ____straight____ line. The slope of the line is the _acceleration_______. This graph is a __linear__ graph. 16. Constant negative acceleration __decreases____ speed. 17. Accelerated motion is characterized by a ____curved____ line. In a nonlinear graph, a _____curve__ connects the data points. 18. What is instantaneous acceleration? Instantaneous acceleration is how fast a velocity is changing at a specific instant. 19. Acceleration involves a change in velocity or direction or both, so the vector of acceleration can point in any ____direction_____. The vectors length depends on how fast __velocity_______is changing. An object that is standing still has an acceleration velocity of _zero_______.