Motion Physical Science

Frame of Reference An object’s motion is related to a fixed body or place Fix = something not moving Common Frame of Reference = The Earth

What is Displacement? The direction from the starting Straight line length distance between starting and ending point Has direction and distance

Combining Displacement Displacement is a vector Vector=quantity with magnitude and direction How to combine vector Same direction, add them Opposite direction, subtract them and give direction to it from highest value’s direction

Examples of Combining Displacement A ball was kicked East 10 meters then it was kicked East 5 meters. How far and in what direction is the ball from the start? Sarah ran 20 meters North from her house before turning around and ran 15 meters South. How far and in what direction is Sarah from her House?

What is SPEED? A rate of motion Change of position (distance) over a period of time

Speed Formula Speed = distance ÷ time s= d/t s = speed (unit = m/s) d = distance (unit = m) t = time (unit = s)

Average verse Instantaneous Speed Average Speed Is calculated for the total distance and total time of the motion Instantaneous Speed Speed at a certain point Speed right NOW

Speed Example Problems Ex #1: Alex rode his motorcycle 600 meters in 15 seconds. How fast did he go?

Speed Example Problems Ex #2: What is the average speed of the car that the graph represent?

What is Velocity? Is speed with a direction Velocity is considered a vector

v = velocity (unit= m/s) Velocity Formula Velocity = distance ÷ time v = d/t v = velocity (unit= m/s) d = distance (unit = m) t = time (unit = s)

End of day one

What is Acceleration Rate of change in velocity Change of velocity in a given time Acceleration is a vector It is where you increase your speed

a= (vf - vi)/t Acceleration Formula a = acceleration (unit = m/s2 or m/s/s) vf = final velocity (unit = m/s) vi = start velocity (unit = m/s) t = time (unit = s)

Deceleration AKA: negative acceleration Solve using acceleration formula except answer is negative It is where you decrease you speed

Acceleration Problem Examples #1 A car starts from rest and accelerates to 20 m/s in 4 seconds. What is the car’s acceleration?

Acceleration Problem Examples #2 A runner is going at a speed of 5 m/s and increases her speed to 55 m/s in a time of 25 seconds. What is the runner’s acceleration?

Acceleration Problem Examples #3 A train slows down from 200 m/s to a stop in 50 seconds. What is the train’s deceleration?

Speed Graphs (distance verse time) Constant Speed Not Moving

Acceleration Graphs (speed verse time) Deceleration Constant Speed

Acceleration Graphs (Distance verse time) Deceleration Constant Speed

End of Day two

Momentum Is the product of the mass of the object and its speed The heavier an object, the harder it is to stop its movement

Momentum Formula p = m * v Momentum = mass * velocity p = momentum (unit = kg*m/s) m = mass (unit = kg) v = velocity (unit = m/s)

Momentum Example Problems #1 At the end of a race, a sprinter with a mass of 80-kg has a speed of 10 m/s. What is the sprinter’s momentum?

Momentum Example Problems #2 A pitcher throws a baseball with a speed of 40 m/s. That baseball has a mass of 0.15-kg. What was the momentum of the baseball?

Momentum (one final important note) Slow moving massive objects and a fast moving small mass object have the same momentum Lets do the math Car 1 Mass= 100kg Velocity= 1 m/s Car 2 Mass= 1kg Velocity= 100 m/s

End of unit