Do Now

• Some Major League pitchers can throw a baseball 100. miles per hour. The ball reaches home plate in less than half a second.
• Convert to meters per second.

Mechanics and Kinematics

CHAPTER 4: LINEAR MOTION

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MS. RUGGIERO

Kinematics

• Mechanics- study of the motion of objects

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• Kinematics- the science of describing the motion of objects using words, diagrams, numbers, graphs, and equations.
• Kinematics is a branch of mechanics.

One way to study motion

• Marks paper at regular time intervals

Ticker Timer

• A ticker timer makes a dot on a paper tape every 1⁄60 of a second (regular time intervals)
• As tape is pulled through the ticker timer, a dot will be made on the tape every 1⁄60 of a second.
• You can use the ticker timer to determine how fast something is moving.
• Provides history of objects motion

• Imagine that the end of the tape is attached to your body. Predict what you think the distance between the dots will look like in each of the following situations. Use phrases such as close together, far apart, or evenly/not evenly spaced to describe the distances between the dots.
• a) You move at a constant speed.
• b) You move at a faster constant speed.
• c) You move at a slower constant speed.
• d) Predict how you think the distance between the dots will change if you walk at a constant speed, and then walk faster and faster.

• The distance between dots on a ticker tape represents the object's position change during that time interval.
• A large distance between dots indicates that the object was moving fast during that time interval.
• A small distance between dots means the object was moving slow during that time interval.

• Ticker tape diagrams are sometimes referred to as oil drop diagrams.

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• Imagine a car with a leaky engine that drips oil at a regular rate.

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• As the car travels through town, it would leave a trace of oil on the street. That trace would reveal information about the motion of the car.

• Renatta Oyle owns such a car and it leaves a signature of Renatta's motion wherever she goes.

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• Analyze the three traces of Renatta's ventures as shown on the next slide. Assume Renatta is traveling from left to right. Describe Renatta's motion characteristics during each section of the diagram.

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• Renatta slows down until she is finally stopped. She remains at rest for a while and then gradually speeds up.

• Renatta travels at a constant speed during the first time interval and then gradually speeds up

Renatta moves with a constant speed in the first time interval. She then slows to a stop. She remains at rest for sometime and then moves with a constant speed, slower than the first speed.