Name: _________________________________________		Date: _______________________________
Science Review-Ch.3 Forces And Motion 				Mrs. Rendon 
Vocabulary 
1. Force: a push or a pull. 
2. Motion: change in position. 
3. Speed: the measure of how fast something moves over a certain distance. 
4. Gravity: the force that pulls objects toward each other.
5. Weight: a measure of the pull of gravity on an object . 
6. Work: the measure of force it takes to move an object a certain distance. 
7. Simple Machine: tool that helps people do work. 

Important Facts
Forces 
1. There are many different forces: 
ex. wind force, car engine, etc. 
2. The amount of force you have to use depend on the mass of the object you want to move: The more mass an  object has, the more force you have to use to make it move. 
Motion 
1. Every motion is started by a force, and every motion is stopped by a force. 
2. Examples of motion: a. Birds flying. 
b. Insects crawling. 
c. Trees moving because of wind breeze.
d. Airplanes traveling in the air.
e. Cars on the road.
f. Falling rain. 
Speed 
1. To find speed, you divide the distance you go by the time it takes you to get there: 
     ex. You are driving from Guayama to San Juan. There are 300 miles of distance and you drive for 3       
           hours. What is the speed?		 (D ÷ T = S)    300 ÷ 3 = 100 mph 
2. Things move at different speeds. There are movements that you cannot see easily. 
     Ex. a. Earth's movement
           b. Wind speed 
c. Glaciers move 30 cms. per day. 
Gravity
1. Because of gravity all things that are dropped fall down. 
2. Gravity pull objects toward each other. The more mass they have, the more gravity pulls toward each other. 
Ex. Mass of Earth is heavy. That's why gravity causes all things near it to fall toward Earth. 
Work 
1. You do work when you:													a. plant a flower 													b. hit a ball 
            c. ride your bike													d. wash your hair
e. put away your clothes 
f. push or pull something to make it move. 
2. You don't do work when you: 
a. push on a door and can't open it.
b. push against the wall. 
c. pull a rope attached to a tree. 
d. Try to open a can without a can opener . 
Simple Machines 
1. A simple machine doesn't change the amount of work, it just make it easier to do. 
2. There are 6 simple machines:												a. lever 
b. pulley 
c. wheel and axle
d. inclined plane
e. wedge
f. screw 

3. There are also compound machines: Machines that are made up of more than one simple machine.