Motion and Forces

​Force & Motion

​Mrs. Coughlin
3rd Grade

3.2 The student will investigate and understand that the direction and size of force affects the motion of an object. Key ideas include

a)      multiple forces may act on an object;

b)      the net force on an object determines how an object moves;

c)      simple machines increase or change the direction of a force; and

d)      simple and compound machines have many applications.

VA Standard of Learning 3.2

A force is an action that changes or maintains the motion of an object.


Simply stated, a force is a push or a pull. Forces can change an object's speed, its direction, and even its shape.

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What is Force?

What are the types of force?

Gravitational - The pulling force from the Earth

Magnetic - The attraction or repelling of a metal object and magnet

Push - moving an object away from you

Pull - moving an object towards you

https://www.youtube.com/watch?v=rnlHxAYwCbg

Watch this demonstration of balanced and unbalanced forces.

Balanced vs. Unbalanced Force

Simple Machines are used to make force easier to apply or to change the direction of an object.

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​Machines Make Motion Easier

Inclined planes are used to move heavy objects from a lower area to a higher area. This requires less force because it is over a longer distance.

​​Inclined Plane

Wedges are an inclined plane used to cut or tear objects apart.

​​Wedge

Screws are an inclined plane wrapped around a rod. They are used to fasten objects together.

​​Screw

​The wheel and axle is used to move heavy loads with very little pulling or pushing force applied.

​​Wheel & Axle

A lever is a rod which rotates around a fulcrum. Can be used to change the direction of an object's motion.

​​Lever

Pulleys, used with a rope, will lower the amount of force needed to lift an object.

Pulley

Compound machines are a combination of one or more simple machines, working together, to make work easier.

....Review!

​Now it's time to see what you know!