210 likes | 351 Views
Chapter 2. Motion. Motion is Relative. When we describe the motion of something, we describe its motion relative to something else Reference point- position in which motion is compared. Speed. Measure of how fast something is moving Speed=Distance/Time Key words: Rate= __________
E N D
Chapter 2 Motion
When we describe the motion of something, we describe its motion relative to something else • Reference point- position in which motion is compared
Speed • Measure of how fast something is moving • Speed=Distance/Time • Key words: Rate= __________ Per= __________
UNITS! • When describing numbers we must always include units • Any combination of distance units over time units is used for speed.
Instantaneous Speed- speed at a particular moment; can be changing • Average Speed- speed over the course of a trip • Average Speed= Total Distance/Time Interval What does the speedometer show? __________
Speed Example Problem • If a car travels 400m in 20 seconds how fast is it going?
Time Example Problem • In a competition, an athlete threw a flying disk 139 meters through the air. While in flight, the disk traveled at an average speed of 13.0 m/s. How long did the disk remain in the air?
Distance Example Problem • How far can you get away from your little brother with the squirt gun filled with paint if you can travel at 3 m/s and you have 15s before he sees you?
Velocity • Speed in a given direction • Example: 60 m/s north
Both cars are moving at 60 km/h • Does this car have constant speed? • Does this car have constant velocity? • Does this car have constant speed? • Does this car have constant velocity
Graphing • Slope= Rise/Run • What is the slope from 0-1 on the x-axis? • What is the slope from 2-3 on the x-axis? • What is the slope from 0-6 on the x-axis?
Acceleration • Rate at which velocity changes • Acceleration= change in velocity/time interval • Change in velocity= Final Velocity- Initial Velocity • Time interval= Final time- Initial time • In science refers to an increase in speed, a decrease in speed, or a change in direction • Can be confusing because it is a rate of a rate
Acceleration • Rate at which velocity changes • Acceleration= Change of Velocity/ Time Interval • In science the word acceleration can me speeding up, slowing down, or changing directions • Acceleration can be confusing because it is a rate of a rate
Acceleration Problem • Toon Train is traveling at the speed of 10 m/s at the top of a hill. Five seconds later it reaches the bottom of the hill and is moving at 30 m/s. What is the rate of acceleration of Toon Train?
Free Fall • 9.8 m/s2= acceleration due to gravity • a=∆v/∆t -We can insert g for a when objects are in free fall • g=∆v/∆t -Which equation should we use to determine velocity? • ∆v=gt -Which equation should we use to determine time? • t=∆v/g
What if you throw an object upward… • What is its change in velocity? ____________
Dollar Bill Activity • Page 21