* Newton's First Law: An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. This means an object's speed won't change without a force.
* Newton's Second Law: The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Acceleration is the rate of change of velocity (speed and direction).
* Net Force: This is the overall force acting on an object after considering all forces and their directions. A net force causes an object to accelerate, which means changing its speed or direction.
Examples:
* Pushing a box: The force you apply to the box changes its speed.
* Gravity pulling an apple: Gravity causes the apple to accelerate downwards, increasing its speed.
* Friction slowing a car: Friction acts as a force opposing the car's motion, causing it to slow down.
Key takeaway: A force is needed to change the speed of an object. This force is the net force, which is the sum of all forces acting on the object.
