Homework Check 300km 364km 250km/hr 120km/hr 2km/m 900km/hr 5km/m
Acceleration In Science, acceleration is defined as the rate at which velocity changes. Acceleration occurs whenever direction and/or speed changes. An increase in velocity is positive acceleration A decrease in velocity is negative acceleration, or deceleration. The faster the velocity changes, the greater the acceleration is.
Acceleration To calculate average acceleration, use the following formula: average acceleration = final velocity – initial velocity time it takes to change velocity The units on acceleration are meters per second per second (m/s/s) or meters per second squared (m/s2)
Acceleration When graphing acceleration, velocity is on the y-axis and time is on the x-axis When velocity is increasing on the graph, your acceleration is positive. When velocity is decreasing on a graph the acceleration is negative. An object traveling in a circle is always changing direction. This means the velocity is always changing. Centripetal acceleration occurs with circular motion.
Acceleration and Velocity-Time Graphs
Acceleration Acceleration is a change in velocity divided by the time it takes for the change to happen. Acceleration can be positive (speeding up) or negative (slowing down).
Practice Problems Maria is jogging. She speeds up from 2 m/s to 8 m/s in 6 seconds. What is her acceleration?
Practice Problems 2. Sarah is driving when she sees a stoplight ahead. She slows down from 30 m/s to 10 m/s in 4 seconds. What is her acceleration?
Practice Problems 3. Tyler is running a race. Near the end, she speeds up, increasing her speed from 7 m/s to 13 m/s in 12 seconds. What is her acceleration?
Practice Problems 4. Kris is riding a bike. He slows down from 18 m/s to 9 m/s in 3 seconds. What is his acceleration?
Velocity-Time Graphs
Interpreting points from v-t graphs Each point has y-coordinate and x- coordinate. Y-coordinate tells you the velocity (speed) of the object at that point. X-coordinate tells you the total time that has passed since object started moving. Point B: (4, 8) x = 4 s y = 8 m/s
Practice At point C, what is the object’s speed, and how much time has passed? After 2 seconds, what was the object’s speed? How many seconds did it take for the object to reach a speed of 6 m/s? At point D, what is the object’s speed?
Calculating acceleration from v-t graphs To find object’s acceleration during an interval: Find the change in speed (y2 – y1) Find the change in time (x2 – x1) Divide change in speed by change in time
Example Acceleration from point A to point B:
Practice What was the acceleration from O to A?
Practice What was the acceleration from A to B?
Practice What was the acceleration from B to C?
Practice What was the acceleration from D to E?
Independent practice time!
Practice What was the acceleration from O to A?
Practice 2. What was the acceleration from A to B?
Practice 3. What was the acceleration from B to C?
Practice 4. What was the acceleration from D to E?
Acceleration Acceleration is a change in velocity divided by the time it takes for the change to happen. Acceleration can be positive (speeding up) or negative (slowing down).
Example Acceleration from point A to point B: