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## Motion Speed, Velocity, Acceleration & Forces

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**Motion**Speed, Velocity, Acceleration & Forces**Frame of Reference**Object or point from which motion is determined**What is Motion?**Motion: A change in position of an object compared to a reference point Motion involves all of the following:**What is motion?**• If you are standing in one place, and your friend walks by you, are you moving relative to your friend? • Is your friend moving relative to you? • Is either of you moving relative to the earth?**Answer:**• You are moving relative to your friend, and your friend is moving relative to you! • You (the Joker) are not moving relative to the earth, but your friend is. You are both moving relative to the sun!**What is motion?**• If you and your friend are walking down the hall together at the same speed, in the same direction, are you moving relative to your friend? • Is your friend moving relative to you? • Are either of you moving relative to the earth?**Answer:**• You are NOT moving relative to your friend, and your friend is NOT moving relative to you. You both are moving relative to the earth.**What is Motion?**= distance time**Speed**Example: A car travels 300km in 6 hours. What is the speed of the car?**Answer:**• Speed = distance ÷ time • Speed = 300km ÷ 6 hours • Speed = 50km/hr**More practice**• 1. How far can a plane travel if it flies 800km/hr for 9 hours? • 2. How long does it take a ship to go 500 km if it travels at a speed of 50km/hr?**Answers**• 7200km/hr • 10 hours**Velocity**• Speed in a given direction. • What is the velocity of a boat that travels from Lancaster to Baltimore(10 miles) in 15 minutes?**Answer**• Speed = distance ÷ time • Speed = 10 miles ÷ 15 minutes • Speed = 0.67 mi/min • Velocity = 0.67 mi/min NW**Acceleration**• Change in velocity • Can be change in speed or direction**Acceleration = Vfinal – Vinitial**• Time or • = ∆Velocity • Time**Acceleration problem**• A roller coaster’s velocity at the top of a hill is 10m/s. Two seconds later it reaches the bottom of the hill with a velocity of 26m/s. What is the acceleration of the roller coaster?**ANSWER:**a = 26m/s – 10m/s 2 s a = 16m/s 2s a = 8m/s/s or 8m/s2**What is a Force?**FORCE = Any push or pull which causes something to move or change its speed or direction**What is a Force?**Forces can be BALANCED or UNBALANCED • Balanced forces are equal in size and opposite in direction • UNbalanced forces are not equal in size and/or opposite in direction. If the forces on an object are UNBALANCED, we say a NET force results.