The Change Of Velocity

SCIENCE CONCEPT:

Acceleration occurs when the velocity of an object changes. Velocity is the speed and direction of an object. Newton's Second Law of Motion defines what happens when a force acts on an object. The object accelerates in the direction in which the force is acting. A force acting on a stationery object starts it moving. A force acting on a moving object will speed it up, slow it down, or change the direction in which it is moving.

STUDENT OBJECTIVE:

The student will create a simple instrument to measure the rate of acceleration of a car you are traveling in.

OVERVIEW:

In the activity, the student will build a measuring instrument from a piece of scrap wood. Using a small toy truck with a stone in its bed the student will measure the rate of acceleration. After building the instrument you will ride in an automobile and measure the rate of acceleration of a car you are traveling in.

PREPARATION TIME:

20 minutes.

LESSON TIME:

40 minutes.

TEACHER PREP:

Gather the materials that will be needed for the experiment.

WORDS TO KNOW:

velocity

acceleration

measurement

rate

mass

matter

weight

force

motion

horizontally

gravity

TEACHER TEXT:

Sir Isaac Newtons Second Law of Motion describes what happens to an object when some force is applied. But, before he could make this connection between force and motion, he needed a way to describe the amount of s in an object.

As an example, you know that it takes more force to throw an iron ball than a tennis ball. An iron ball is heavier than a tennis ball, but it is not the weight that makes it harder to throw. If there were no gravity, so that the balls had no weight, the iron ball would still be harder to throw. The iron ball has a greater amount of matter or material in it and matter resists being accelerated. Newton called the measure of the amount of material in an object its mass.

Mass is the resistance to being accelerated and weight is the force of the earths gravity pulling on an object. An object has the same mass everywhere in the universe. It has weight only where there is gravity. Matter resists being accelerated and the greater the mass the greater the force that will be needed to accelerate it. Matter also has the property of being attracted by gravity. The more matter there is the greater is the force of gravity on that object.

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Last modified: Sat Nov 15 19:04:46 PST 1997