Describing and Measuring Motion 1.Motion – An object is in motion when its distance from another object is changing. 2.Reference Point – A place or object used for comparison to determine if something is moving. For example, the Sun is a reference point for the Earth.

Describing and Measuring Motion 3. Describing Distance – The basic metric unit for length is the meter (m). 1m = 100 cm = 1000 mm 1 km = 1000 m 4.Calculating Speed – The distance the object travels in one unit of time. Speed = Distance/Time Speed = m/s, km/h, mi/h

Describing and Measuring Motion 5.Constant Speed – If the speed of an object does not change the object is traveling at a constant speed. The speed of the object is the same at all times. 6.Average Speed – Most objects do not move at constant speeds for very long. Think of a cyclist going up a hill then down the hill then onto a flat road. Avg. Speed = 32 km + 13 km =45 km = 15 km 2 h + 1 h = 3 h = h 7.Velocity – Speed in a given direction is called Velocity. Ex. 50 km/h due North

Describing and Measuring Motion 8. Graphing Motion -

Describing and Measuring Motion 9.Tectonic Plates – Earth’s rocky outer shell consists of broken pieces that fit together like a jigsaw puzzle. The upper layer of the Earth consists of more than a dozen major pieces of rock called tectonic plates. 10.Theory of Tectonic Plates – According to this theory the Earth’s plates move ever so slowly in various directions. Ex. 5 cm/yr x 1000 yr = 5000 cm = 50 m

Describing and Measuring Motion 11.Acceleration – The rate at which velocity changes. In science, acceleration refers to increasing speed, decreasing speed, or changing direction. 12.Increasing Speed – A softball as the pitcher throws it. A car that is stopped and then moves forward. A car that speeds up to pass another car. 13.Decreasing Speed – A softball as it rolls to a stop. A car that comes to a stop at a red light. A jet landing on an aircraft carrier.

Describing and Measuring Motion 14. Changing Direction – A car moving at constant speed through a gentle curve. A car changing lanes.

Describing and Measuring Motion 15.Acceleration Calculation – Acceleration = Final Velocity – Initial Velocity Time Final Velocity = 40 m/s Initial Velocity = 0 m/s Time = 5 sec. Acceleration = 40 m/s – 0 m/s 5 sec. = 8 m/s/s = 8m/s 2

Describing and Measuring Motion 16.Which of the cars is constantly accelerating?

Describing and Measuring Motion 17.Graphing Acceleration -