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Newton’s Second Law of Motion• Acceleration of an object depends on the force and mass.While Newton’s First Law describes how objects behave when forces are balanced, hissecond law is about what happens when two forces are unbalanced. Newton’s Second Lawsays that once an object is set in motion, its acceleration will depend on two things: force andmass.In fact, this law of motion is often expressed as an equation:Force equals mass timesacceleration(F = ma).Force and acceleration are proportional to each other—the amount of force is equal tothe amount of acceleration.The greater the force exerted on an object, the more it willaccelerate. For example, the harder you kick a ball, the farther and faster it will travel.The opposite is true of mass.The more mass an object has, the less it will accelerate. If youkick a tennis ball and a bowling ball with the same amount of force, the heavy bowling ball isgoing to move slower and go a shorter distance than the tennis ball. A heavier objectrequires more force to set it in motion.Newton’s Third Law of Motion• For every action, there is a reaction that is equal in magnitude and opposite indirection.Forces always occur in pairs, and Newton’s Third Law of Motion helps us understand therelationship between pairs of forces. Every time a force, or action, occurs, it causes a reaction.We can describe the reaction in terms of its strength, or magnitude, and also its direction.The magnitude of the action is equal to the magnitude of the reaction. For example, if youtoss a pebble into the water, it’s going to create a small ripple or splash. If you hurl a largeboulder at the water, the splash is going to be bigger.The force of the action and reactionalways match up.While an action and its reaction are equal in magnitude, they are opposite in direction.The rock plunges down into the water, but the water splashes up.When you throw or shootsomething forward, the recoil of the force pushes you backward. Every time a force acts on anobject, it causes a reaction force in the opposite direction.Kinetic & Potential EnergyEnergyis the ability to do work. An object doesn’t have to be in motion to possessenergy.Potential energyis energy that’s stored in an object. (In fact, it’s also referred to asstored energy.) An object’s position or circumstances give it potential energy. A spring onthe bottom of a pogo stick has potential energywhen someone is standing on the pogostick.The coil of the spring compresses when pressure is applied, storing up energy that willlater be released.The more height and mass an object has, the more gravitational potentialenergy it has.Once an object is in motion, it has kinetic energy.When the spring compresses andreleases, the kinetic energy of the spring pushes the pogo stick and its rider up into the air.When the person jumps on the pogo stick and the spring compresses again, more potentialenergy is stored in the spring.When the spring releases, the kinetic energy of the springpushes the rider up once again.