Grade 10 Science: Unit 1 In Motion Introduction Grade 10 Science: Unit 1 In Motion

Grade 10 Science In grade 9 you learnt your different science units based off of different science concepts. The hope was that you learnt the science behind different concepts and tried to apply them to your real life. In grade 10 science, the reason for the ‘In Motion’ unit is very similar, but also a lot more personal.

“Motor vehicle crashes 2004 United States NHTSA “Motor vehicle crashes are the leading cause of death for 15- to 20- year-olds.”

In Motion Motion is defined as the movement of an object, or any of its parts, from one place to another. The study of the motion of objects and the forces that affect their motion is called mechanics.

Categories Mechanics is divided up into two distinct categories: Kinematics Dynamics

Kinematics The description of the motion of objects without considering the cause of the motion.

Dynamics An examination of the causes of the motion and an explanation of why the objects move as they do.

KINEMATICS Lesson 1: Describing motion with words The language of Kinematics

Kinematics Kinematics is the science of describing the motion of objects using words, diagrams, numbers, graphs, and equations. The goal of any study of kinematics is to develop sophisticated mental models which serve us in describing (and ultimately, explaining) the motion of real- world objects.

Scalars and Vectors Scalars are quantities which are fully described by a magnitude alone. Vectors are quantities which are fully described by both a magnitude and a direction.

Check Your Understanding To test your understanding of this distinction, consider the following quantities listed below. Categorize each quantity as being either a vector or a scalar.

5 m 3 m/s East 30 mi North 20 degrees Celsius -

Distance and Displacement These do NOT mean the same thing. Distance is a scalar quantity which refers to "how much ground an object has covered" during its motion. Displacement is a vector quantity which refers to "how far out of place an object is"; it is the object's change in position.

Position The location of an object relative to a reference point. A vector quantity because direction must be specified. Displacement is described as the change in position of the object.

Example A physics teacher walks 4 meters East, 2 meters South, 4 meters West, and finally 2 meters North. Even though the physics teacher has walked a total distance of 12 meters, her displacement is 0 meters.

Example The diagram below shows the position of a cross-country skier at various times. At each of the indicated times, the skier turns around and reverses the direction of travel. In other words, the skier moves from A to B to C to D. Use the diagram to determine the resulting displacement and the distance traveled by the skier during these three minutes.

Diagram A

Solution The skier covers a distance of 420 meters (180 m + 140 m + 100 m). The skiers displacement is 140 m Right.

Example Seymour views football games from under the bleachers. He frequently paces back and forth to get the best views. The diagram below shows several of Seymour's positions at various times.

Solution Seymour covers a distance of 95 yards, (35 yds + 20 yds + 40 yds). His total displacement is 55 yards, left.