Chapter 6: Lesson 1

Chapter 6: Lesson 1

The Nature of Force​

By Teresa Greiner

Acceleration

Acceleration: the rate at which velocity changes

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• Velocity describes both the speed and direction of an object​

• A change in velocity can involve a change in either speed or direction- or both ​

• In science, acceleration refers to increasing speed, decreasing speed, or changing direction​

Changing Speed

• Whenever an object's speed changes, the object accelerates

• When an object slows its speed​, it can be called "deceleration" or negative acceleration

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Examples: ​

• A car decelerates as it comes to stop at a red light

• A water skier decelerates as a boat slows down ​

Changing Direction

• Acceleration can be a change in direction, so when a car changes lanes or follows a curve in the road, it is accelerating

• A baseball accelerates when it changes direction as its hit

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• Circular motion- motion along a circular path​

calculating Acceleration​

Acceleration = (Final Speed - Initial Speed) / Time

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Final speed minus Initial speed- divided by Time​

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​Acceleration = m/s²

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How are forces described?

A force is a push or a pull

• When one object pushes or pulls another object, the first object exerts a force on the second object

• Examples: You exert force on a computer key when you push it

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Force is described by its strength and by the direction in which it acts

The strength of a force is measured in the SI Unit called the newton (N) ​

Net force

• More than one force can act on an object at once

• The combination of all the forces on an object is called the net force​

• A non zero net force causes a change in the object's motion

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Net Force

• ​When forces on an object act in opposite directions, the strength of the net force is found by subtracting the strength of the smaller force from the strength of the larger force

• When forces act in opposite directions, the net force is in the same direction as the larger force​

​7N to the LEFT

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10N to the RIGHT

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10 - 7 = 3

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3N to the LEFT​