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An elaboration on how to use Newton's second law when dealing with multiple forces, forces in two dimensions, and diagonal forces.

An elaboration on some of the common misconceptions in dealing with Newton's Third Law. He also shows how to correctly and reliably identify Third Law force pairs.

This unit is about how things move along a straight line or, more scientifically, how things move in one dimension. Examples of this would be the movement (motion) of cars along a straight road or of trains along straight railway tracks.

In this lesson you will learn:

• to distinguish between distance and displacement
• to distinguish between speed and velocity
• understand acceleration
• interpret time-velocity graphs
• use equations of uniformly accelerated motion
• understand the concept of gravitational force

In this chapter, we’ll use vectors to expand our understanding of forces and motion into two dimensions. Most real-world physics problems (such as with the game of pool pictured here) are, after all, either two- or three-dimensional problems and physics is most useful when applied to real physical scenarios. We start by learning the practical skills of graphically adding and subtracting vectors (by using drawings) and analytically (with math). Once we’re able to work with two-dimensional vectors, we apply these skills to problems of projectile motion, inclined planes, and harmonic motion.

Basic primer on Newton's First Law of motion.

Newton's Laws of Motion

Newton's second law of motion is F = ma, or force is equal to mass times acceleration. Learn how to use the formula to calculate acceleration.

Learn about Newton's third law of motion, which states that for every action there is an equal and opposite reaction. Look at multiple examples that illustrate this law, including pushing a block on ice, pushing against a desk, walking on sand, how rockets work, and how an astronaut could save themselves from drifting in space.

• Predict how current will change when resistance of the circuit is fixed and voltage is varied.
• Predict how current will change when voltage of the circuit is fixed and resistance is varied.