Speed, Velocity, and Acceleration Motion Speed, Velocity, and Acceleration

MOTION Motion is easy to recognize but can be hard to describe The following quantities are used to describe motion: speed, velocity and acceleration Each of these is a rate. A rate is a quantity divided by time.

Frames of Reference Object or point from which motion is determined Most common is the Earth Motion is a change in position relative to a frame of reference

Describing 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.

Speed Speed is a measure of how fast something is moving. It is the rate at which a distance is covered Units of speed could be: km/h, m/s, mi/h, ft/s

Speed Definitions: Speed The rate at which something moves a given distance. Faster speeds = greater distances General formula for speed: Speed = distance / time

Speed Speed = Distance ÷ Time 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

Speed Practice Problems 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?

Answer 1. D S T D 800 9 800km ▪ 9hrs = 7200km hr

Answer 2. D S T 500 50 T 500km ÷ 50km = 10 hrs hr

Velocity Speed in a given direction. Again , Speed in a given direction. Velocity is speed in a give direction!!!!!

Velocity Practice Problem 1. What is the velocity of a boat that travels from Nashville to Huntsville (10 miles) in 15 minutes?

Answer Speed = distance ÷ time Speed = 10 miles ÷ 15 minutes Speed = 0.67 mi/min Velocity = 0.67 mi/min South

Acceleration Definition Formula Acceleration is a measure of how quickly the velocity changes Formula a = Dv/t What does the D mean? – The Greek letter D represents change. D V means a change velocity.

Acceleration For its velocity to change, an object must accelerate. An object accelerates whenever its speed or direction or both change. Acceleration may be positive (increasing speed) or negative (decreasing speed).

The 3 Types of Acceleration Speeding Up Slowing Down Turning

Acceleration at Constant Speed An object moving in a circle at constant speed is always accelerating (changing direction).