Speed and Acceleration Lesson Notes PDF

At the Berlin 2009 World Championships, Usain Bolt of Jamaica made a world record of 9.58 seconds for the 100m race. Calculate his average speed in this record- breaking race. Speed LO and SC: 0:01...

At the Berlin 2009 World Championships, Usain Bolt of Jamaica made a world record of 9.58 seconds for the 100m race. Calculate his average speed in this record- breaking race. Speed LO and SC: 0:01 0:02 0:03 0:04 0:05 0:06 0:07 0:08 0:09 0:10 0:11 0:12 0:13 0:14 0:15 0:16 0:17 0:18 0:19 0:20 0:21 0:22 0:23 0:24 0:25 0:26 0:27 0:28 0:29 0:30 0:31 0:32 0:33 0:34 0:35 0:36 0:37 0:38 0:39 0:40 0:41 0:42 0:43 0:44 0:45 0:46 0:47 0:48 0:49 0:50 0:51 0:52 0:53 0:54 0:55 0:56 0:57 0:58 0:59 1:00 1:01 1:02 1:03 1:04 1:05 1:06 1:07 1:08 1:09 1:10 1:11 1:12 1:13 1:14 1:15 1:16 1:17 1:18 1:19 1:20 1:21 1:22 1:23 1:24 1:25 1:26 1:27 1:28 1:29 1:30 1:31 1:32 1:33 1:34 1:35 1:36 1:37 1:38 1:39 1:40 1:41 1:42 1:43 1:44 1:45 1:46 1:47 1:48 1:49 1:50 1:51 1:52 1:53 1:54 1:55 1:56 1:57 1:58 1:59 2:00 End (Speed) LO: Understanding the concept of speed SC: Must – Define speed as distance travelled per unit time; recall and use the equation Should – Recall and use the equation Could – Define acceleration as change in velocity per unit time; recall and use the equation a =Δv/Δt – Know that a deceleration is a negative acceleration and use this in calculations  Kinematics Kinematics is the branch of mechanics concerned with the motion of objects without reference to the forces which cause the motion. The key concepts in kinematics includes:  Distance traveled  Speed  Acceleration  Speed Speed is a measure of how fast an object is moving. Speed can be calculated using the equation: What is the unit used for speed?  Sample questions: 1) Benwalks 200 metres in 40 seconds. What is his speed? 2) Andycovers 2 km in 1,000 seconds. What is his speed? 3) Howlong would it take Connor to run 100 metres if he could run at 12m/s? 4) Dan throws a book at Adam and it travels at 50m/s for 0.2s. How far away was Adam?  Average speed The speed of an object usually changes over time. That is, it does not have a constant speed throughout the journey. For example: Your commute to school this morning. 𝑡𝑜𝑡𝑎𝑙𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 We can calculate the average speed as: 𝑎𝑣𝑒𝑟𝑎𝑔𝑒 𝑠𝑝𝑒𝑒𝑑= 𝑡𝑜𝑡𝑎𝑙𝑡𝑖𝑚𝑒  Sample question Suppose a truck travels in segments that are described in the following Segment table: Distance Time (km) (hours) 1 50 1.5 2 35 1.0 3 50 1.5 Determine the: 4 75 2.5 a) Total distance traveled Ans: a) 210 km b) Total time taken b) 6.5 hours c) Average speed of the entire journey c) 32.3  Sample question John drove for 3 hours at a rate of 50 km/h and for 2 hours at 60 km/h. What was his average speed for the whole journey? Total distance traveled = Total time taken = 3 + 2 = 5 hours Average speed = 54 km/h  Acceleration  Acceleration is defined as the rate of change of speed.  We can calculate the acceleration as: 𝑐h𝑎𝑛𝑔𝑒𝑖𝑛 𝑠𝑝𝑒𝑒𝑑 𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛= 𝑡𝑖𝑚𝑒𝑡𝑎𝑘𝑒𝑛 ∆𝑣 𝑣 −𝑢 𝑎= 𝑎= 𝑡 𝑡  Unit = m/s2 A car accelerates from 25 m/s to A cyclist travels from a stationary 35m/s in 5 seconds. Calculate its position and reaches a velocity of 36 acceleration. m/s in 8 seconds. What is the acceleration of the car? A car is traveling at 18 m/s when its The initial speed of a cart is 15 m/s. driver presses on the accelerator. After 3 seconds, it has a new speed of Calculate the time it takes for it to 6 m/s. Determine its acceleration. come achieve a speed of 45 m/s, assuming it experiences a constant acceleration of 3 m/s2.  Acceleration and Deceleration Acceleration Deceleration  Increase in speed  Decrease in speed  Positive acceleration  Negative acceleration LO and SC: 0:01 0:02 0:03 0:04 0:05 0:06 0:07 0:08 0:09 0:10 0:11 0:12 0:13 0:14 0:15 0:16 0:17 0:18 0:19 0:20 0:21 0:22 0:23 0:24 0:25 0:26 0:27 0:28 0:29 0:30 0:31 0:32 0:33 0:34 0:35 0:36 0:37 0:38 0:39 0:40 0:41 0:42 0:43 0:44 0:45 0:46 0:47 0:48 0:49 0:50 0:51 0:52 0:53 0:54 0:55 0:56 0:57 0:58 0:59 1:00 1:01 1:02 1:03 1:04 1:05 1:06 1:07 1:08 1:09 1:10 1:11 1:12 1:13 1:14 1:15 1:16 1:17 1:18 1:19 1:20 1:21 1:22 1:23 1:24 1:25 1:26 1:27 1:28 1:29 1:30 1:31 1:32 1:33 1:34 1:35 1:36 1:37 1:38 1:39 1:40 1:41 1:42 1:43 1:44 1:45 1:46 1:47 1:48 1:49 1:50 1:51 1:52 1:53 1:54 1:55 1:56 1:57 1:58 1:59 2:00 End (Speed and acceleration) LO: Understanding the concept of speed and acceleration SC: Must – Define speed as distance travelled per unit time; recall and use the equation Should – Recall and use the equation Could – Define acceleration as change in velocity per unit time; recall and use the equation a =Δv/Δt – Know that a deceleration is a negative acceleration and use this in calculations