Key Idea.
Section 1
Forces Have Strength and Direction
Every force is a push or a pull that has two important features: strength and direction. The direction is where the force is going, like pushing a car forward or pulling a wagon backward.
The strength is how hard the force is pushing or pulling. A gentle push is a small force, while a hard shove is a strong force. When we look at why things move or stay still, we must look at both the strength and direction of the forces.
Section 2
Multiple Forces Act at Once
Often, an object has more than one force acting on it at the same time. This is a situation of multiple forces.
Think of a book on a table. Gravity is pulling the book down. At the same time, the table is pushing the book up. Even though the book looks like it is doing nothing, there are actually two forces acting on it at once: one pulling down and one pushing up.
Expand to review the lesson summary and core properties.
Section 1
Forces Have Strength and Direction
Every force is a push or a pull that has two important features: strength and direction. The direction is where the force is going, like pushing a car forward or pulling a wagon backward.
The strength is how hard the force is pushing or pulling. A gentle push is a small force, while a hard shove is a strong force. When we look at why things move or stay still, we must look at both the strength and direction of the forces.
Section 2
Multiple Forces Act at Once
Often, an object has more than one force acting on it at the same time. This is a situation of multiple forces.
Think of a book on a table. Gravity is pulling the book down. At the same time, the table is pushing the book up. Even though the book looks like it is doing nothing, there are actually two forces acting on it at once: one pulling down and one pushing up.