Define MOTION Seconds Remaining 140 120 130 30

Define MOTION Seconds Remaining: 140 120 130 30 40 50 60 70 10 2 3 4 5 6 7 8 9 0 180 20 160 90 170 150 100 110 180

Motion: Change in position of an object relative to a reference point.

Describe SPEED and VELOCITY Seconds Remaining: 140 120 130 30 40 50 60 70 10 10 280 3 4 5 6 7 8 9 180 20 160 90 170 150 100 110

• SPEED - is the rate of motion, or the rate of change of position; – a measurement of distance traveled over time – calculated by dividing the distance traveled by the time taken • VELOCITY - measurement of the rate and direction of motion – an object's speed and direction of motion

Describe Friction Seconds Remaining: 140 120 130 30 40 50 60 70 10 2 3 4 5 6 7 8 9 0 180 20 160 90 150 170 100 110 180

FRICTION - the resistance to motion encountered when one body is moved in contact with another Force opposing motion of two objects that are in contact.

Describe ACCELERATION SECONDS REMAINING: 140 120 130 30 40 50 60 70 10 2 3 4 5 6 7 8 9 0 180 20 160 90 170 150 100 110 180

• ACCELERATION - The rate at which an object's velocity changes with time. – The rate of change of velocity. – Change in speed or change of direction.

Create a diagram of a distance-time graph and a velocity-time graph SECONDS LEFT: 140 120 130 30 40 50 60 70 10 2 3 4 5 6 7 8 9 0 180 20 160 90 150 170 100 110 180

A student stands on a skateboard as the skateboard remains in place. When the student pushes his foot against the ground, the skateboard moves forward. The harder he pushes against the ground, the faster the skateboard moves. A friend jumps on for a ride, and the skateboard slows down. The student must push even harder to get the skateboard moving again. Once they get going, they hit a curb. The skateboard stops moving, but the students fly onto the grass. Fortunately, everyone is fine. Seconds Remaining: 120 140 130 70 60 50 40 30 10 9 8 7 6 5 4 3 2 0 180 20 160 90 80 170 150 110 100 180 – Describe three instances in the above paragraph where the skateboard was under the influence of unbalanced forces. For each instance, identify the primary forces involved, and explain why they were unbalanced.

Three situations where the skateboard is under the influence of unbalanced forces are: 1. The student giving the initial push to move the skateboard — unbalanced between acceleration by the student and friction, as the skateboard started moving. 2. Friend jumps on the skateboard — unbalanced between acceleration by the student and friction, as the skateboard started slowing down. 3. Hitting the curb — unbalanced between acceleration by the student and force exerted by the curb, as the skateboard stops moving.

A group of students split up into two groups of four for a tug-of-war. Each group pulls on one end of a heavy rope. – Draw a diagram showing what happens when the forces on the rope are balanced. The forces involved should be represented by arrows, and any motion should be drawn and labeled. Your diagram should include the students pulling on the rope. Seconds Remaining: 120 140 130 70 60 50 40 30 10 9 8 7 6 5 4 3 2 0 180 20 160 90 80 170 150 110 100 180

A person jumps out of an airplane. At first, the person speeds up during the fall. But then, the person falls at a constant velocity known as terminal velocity. – Identify the two primary forces acting on the person during the fall. Seconds Remaining: 120 140 130 70 60 50 40 30 10 9 8 7 6 5 4 3 2 0 180 20 160 90 80 170 150 110 100 180

The person experiences the primary forces of gravity and air resistance during the fall.

Explain inertia Seconds Remaining: 120 140 130 70 60 50 40 30 10 9 8 7 6 5 4 3 2 0 180 20 160 90 80 170 150 110 100 180

An object in motion will remain in motion (keep moving), and an object at rest will remain at rest (not move) unless acted upon by an outside force.

A student stands on a skateboard as the skateboard remains in place. When the student pushes his foot against the ground, the skateboard moves forward. The harder he pushes against the ground, the faster the skateboard moves. A friend jumps on for a ride, and the skateboard slows down. The student must push even harder to get the skateboard moving again. Once they get going, they hit a curb. The skateboard stops moving, but the students fly onto the grass. Fortunately, everyone is fine. – Describe three instances in the above paragraph where the skateboard was under the influence of unbalanced forces. For each instance, identify the primary forces involved, and explain why they were unbalanced. Seconds left: 140 120 130 30 40 50 60 70 10 2 3 4 5 6 7 8 9 0 180 20 160 90 170 150 100 110 180

Three situations where the skateboard is under the influence of unbalanced forces are: 1. The student giving the initial push to move the skateboard — unbalanced between acceleration by the student and friction, as the skateboard started moving. 2. Friend jumps on the skateboard — unbalanced between acceleration by the student and friction, as the skateboard started slowing down. 3. Hitting the curb — unbalanced between acceleration by the student and force exerted by the curb, as the skateboard stops moving.

A student stands on a skateboard as the skateboard remains in place. When the student pushes his foot against the ground, the skateboard moves forward. The harder he pushes against the ground, the faster the skateboard moves. A friend jumps on for a ride, and the skateboard slows down. The student must push even harder to get the skateboard moving again. Once they get going, they hit a curb. The skateboard stops moving, but the students fly onto the grass. Fortunately, everyone is fine. Describe one instance in the above paragraph where the skateboard was under the influence of balanced forces. Identify the primary forces involved, and explain why they were balanced. Seconds Left: 140 120 130 30 40 50 60 70 10 2 3 4 5 6 7 8 9 0 80 180 20 160 90 170 150 100 110 1

A situation where the skateboard is under the influence of balanced forces is: 1. The student standing on the skateboard as it remains in place — balanced between gravity and force exerted by the ground, as the skateboard remains motionless.

The speed of a person riding a bicycle on a level, straight road is measured and plotted in the above graph. – Identify and describe the two primary factors acting on the bike that affect its speed for each of the following time periods: – 0 min. to 1 min. – 2 min. to 3 min. – 1 min. to 2 min. – 3 min. to 4 min. Seconds Left: 140 120 130 30 40 50 60 70 10 2 3 4 5 6 7 8 9 0 180 20 160 90 150 170 100 110 180

Acceleration by the biker and the friction are the primary forces acting on the bike that affect its speed. During period 1, the forces are unbalanced, because the bike is slowing down. During period 2, the forces are balanced, because the bike's speed stays constant. During period 3 the forces are unbalanced, because the bike is speeding up. During period 4, the forces are balanced, because the bike's speed stays constant.

In what direction is the force of friction exerted? Seconds Left: 120 140 130 70 60 50 40 30 10 180 20 160 900234567891 80 170 150 110 100

The force of friction is exerted opposite to the direction of motion

What are two ways you can change your velocity? Seconds left: 140 120 130 30 40 50 60 70 10 2 3 4 5 6 7 8 9 0 180 20 160 90 170 150 100 110 180

Change speed or change direction

What is a net force? Seconds Left: 140 120 130 30 40 50 60 70 10 2 3 4 5 6 7 8 9 0 180 20 160 90 150 170 100 110 180

A net force is the sum of the forces acting on an object

Describe work Seconds Left: 120 140 130 70 60 50 40 30 10 9 8 7 6 5 4 3 2 0 180 20 160 90 80 170 150 110 100 180

Work is done when a force causes an object to move in the direction of the force.