Motion

Physics

• Science that involves matter and its motion through space and time.

• We just finished Chemistry: Study of the properties and behavior of matter.

Distance and Displacement

Distance and Displacement

• How fast is this lady running?

• Earth spins at 1670 km/hr

• And it is moving around the sun at 107,000 km/hr

Distance and Displacement

• To describe motion accurately, a frame of reference is necessary.

• Frame of reference is a system of objects who are not moving with respect to one another.

– Ex: Earth is the “stationary” frame of reference when cops measure the speed of our cars.

Measuring Distance

• Distance: the length of a path between two points

• Classroom examples?

Measuring Distance

• The SI unit for measuring distance is the Meter (m).

• WE WILL NOT BE USING MILES, FEET, or INCHES in Science class!!

• Why do we use metric?

Measuring Distance

• Large distances are measured in Kilometers (km).

• One kilometer is equivalent to how many meters?

• One centimeter is one hundredth of a meter!

Measuring Displacement

• What is distance?

• Displacement: The DIRECTION from the starting point and the LENGTH of a straight line from the starting point to the ending point.

Measuring Displacement

• Walk 10 blocks

• Walk 10 blocks north from Kroger

Combining Displacements

• Vector: Quantity that has magnitude and direction.

• Magnitude can be size, length, or amount.• Arrows are used to represent vectors.• Size of the arrow corresponds to magnitude

(size)

Combining Displacements

• Vector addition is the combining of vector magnitudes and directions.

• Add displacements using vector addition.

Combining Displacements

• Displacements along a straight line.

Combining Displacements

Combining Displacements

Combining Displacements

Combining Displacements

Combining Displacements

Displacement that isn’t Along a Straight Path

• Resultant Vectors: Vector sum of 2 or more vectors.

Speed and Velocity

• Speed– Average speed– Instantaneous speed

• Graphing Motion• Velocity• Combining Velocities

Speed

• Speed: The ratio of the distance an object moves compared to the amount of time the object moves.

• SI unit for speed is meters/second (m/s).

• If a car travels 40 km in 5 hours, how fast is the car moving?

Speed

• Average Speed: Computed for the ENTIRE DURATION of the trip.

• Instantaneous Speed: Measured at a particular instance.

Average Speed

• Average speed (v) = total distance traveled (d) divided by the total time (t).

Average Speed

Average Speed

Average Speed

Average Speed

Instantaneous Speed

• Instantaneous Speed: The rate at which an object is moving at a given moment in time.– A car’s speedometer measures instantaneous

speed.

Graphing Motion