1. A force is a pushing or pulling effect on an object by another object.
2. A force cannot be seen but only the effects of a force can be seen and felt.
DID YOU KNOW? You can't see a force, but you can always see what it does! When you push a door open, the door moving is the EFFECT of your force. Forces are invisible "doers" that make things happen.
1. A force can cause a stationary object to start moving.
Example: A stationary golf ball rolls when it is hit by a golf club.
2. A force can change the speed of a moving object.
Example: When a driver steps harder on the accelerator, the engine works more to move the car faster.
3. A force can also change the direction of motion of a moving object.
Example: When a moving ball is kicked from a certain direction, its direction of motion changes (e.g., East → Southeast).
4. A force can also change the size and shape of an object.
Example: When a load is hung on a spring, the spring lengthens.
5. A force can also cause a turning effect on an object.
Example: When a force turns and pulls the doorknob, the door rotates about the hinges and opens.
⚠️ Remember: A force is a PUSH or PULL
It can make things START, STOP, SPEED UP, SLOW DOWN, CHANGE DIRECTION, CHANGE SHAPE, or TURN.
1. A rubber band stretches when it is pulled apart. When the applied force is removed, the elastic spring force in the stretched band returns it to its original shape and size.
2. Friction is the force that opposes motion. It occurs when two surfaces slide or try to slide across each other.
3. The push or pull between two magnets is a magnetic force. This force acts over a distance without the magnets touching each other. This force occurs when two magnetic poles interact.
4. When unlike poles face each other, the magnets pull or attract each other.
5. When like poles face each other, the magnets push away or repel each other.
6. The pulling force exerted by the Earth on all objects is the gravitational force.
DID YOU KNOW? Magnetic force is one of the few forces that can work WITHOUT touching! A magnet can attract a paperclip from a distance. This is called an "action at a distance" force. Gravity works the same way — Earth pulls you down without touching you!
1. The weight of an object is the force of gravity acting on the object.
2. The mass of an object is the amount of matter contained in the object.
3. The weight of an object changes with the distance of the object from Earth. The mass of an object remains the same anywhere.
DID YOU KNOW? An astronaut's MASS is the same on Earth and the Moon, but their WEIGHT is about 6 times LESS on the Moon! That's why astronauts can jump so high there — gravity pulls them down much less. But they still have the same amount of "stuff" (matter) inside them!
📝 Interaction of Forces — Quick Summary
💪 Force = Push or Pull (invisible, effects visible)
🕸️ 5 Effects: Start moving, Change speed, Change direction, Change size/shape, Turning effect
🧪 Types: Elastic Spring, Friction, Magnetic, Gravitational
🧈 Magnets: Unlike poles attract, Like poles repel
⚖️ Weight changes with distance, Mass stays the same