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A **force** is a push or pull acting on an object. For example, friction can act in the opposite direction of a sliding motion and slows the motion down.

**Newton's First Law of Motion** states that an object at rest stays at rest and an object in motion will remain in motion at a constant velocity in a straight line. How does **inertia** relate to this law?

However, if an unbalanced force acts on an object, the object will accelerate. **Newton's Second Law of Motion** helps clarify the relationships concerning mass, acceleration, and force. It states that the acceleration of an object is directly proportional to the net force on the object and inversely propertional to the mass of the object. In other words: **F _{ }= ma**. How does mass affect the acceleration? What affects the direction of the acceleration?

**Remember:** the units of force are Newtons (N), which is equivalent to \begin{align*}\frac{kg \cdot m}{s^2}\end{align*}.

Using Newton's Second Law of Motion, how much force is required to accelerate a 1500. kg car at 5.000 m/s^{2}? (To check your answer, highlight the following: 7500. N)

If the net force acting on a block of 2.5 kg is 150 N, what is its acceleration? (To check your answer, highlight the following: 60. m/s^{2})

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