Motion S8P3. Students will investigate relationship between force, mass, and the motion of objects. a. Determine the relationship between velocity and acceleration.

Motion Measuring Motion  Motion  Speed & Velocity  Acceleration

Motion Motion is when an object changes position over time relative to a reference point. Problem:  Is your desk moving? We need a reference point...  a nonmoving or moving point from which motion is measured

Motion Superman Example  The speeding bullet is a moving reference point to Superman’s motion.  The tall building is the non-moving reference point when Superman leaps.

Motion Motion  Change in position in relation to a reference point. Reference point Motion

Motion Problem: You are a passenger in a car stopped at a stop sign. Out of the corner of your eye, you notice a tree on the side of the road begin to move. What’s the problem? You have mistakenly set yourself as the reference point.

Speed Speed  rate of motion  distance traveled by an object in a given amount of time s d t Write Formula

Speed Instantaneous Speed  speed at a given instant Average Speed Write Formula

Speed Problem:  A storm is 10 km away and is moving at a speed of 60 km/h. Should you be worried?  It depends on the storm’s direction!

Velocity Velocity  speed of an object in a given direction  changes when speed and/or direction changes  Examples: The car’s velocity was 104 km/h N (about 65 mph N). John’s velocity was 1 m/s S (about 2.2 mph S) The runner’s velocity was 37 km/h W (about 23 mph W).

Graphing Motion slope = steeper slope = straight line = flat line = Distance-Time Graph A B faster speed constant speed no motion speed

Graphing Motion Who started out faster?  A (steeper slope) Who had a constant speed? AA Describe B from min.  B stopped moving Find their average speeds.  A = (2400m) ÷ (30min) A = 80 m/min  B = (1200m) ÷ (30min) B = 40 m/min Distance-Time Graph A B

Acceleration Acceleration  the rate of change of velocity  change in speed and/or direction a: acceleration v f : final velocity v i : initial velocity t: time a v f - v i t Write Formula

Acceleration The velocity can change even when the speed is constant! Examples: 25 m/s S  25 m/s E 55 m/s W  20 m/s W

Acceleration Positive acceleration  “speeding up”  Ex. 5 km/h  25 km/h Negative acceleration (Deceleration)  “slowing down”  Ex. 25 km/h  5 km/h

Acceleration

Distance-Time Graph Graphing Motion Acceleration is indicated by a curve on a Distance-Time graph. Changing slope = changing velocity

Graphing Motion Speed-Time or Velocity-Time Graph slope = acceleration  “+” velocity = speeds up  “-” velocity = slows down Straight line = constant acceleration flat line = constant speed

Graphing Motion Speed-Time or Velocity-Time Graph Specify the time period when the object was... slowing down  5 to 10 seconds speeding up  0 to 3 seconds moving at a constant speed  3 to 5 seconds not moving  0 & 10 seconds