1 Forces change the motion of an object in very specific ways. So specific in fact that scientist and inventor, Sir Isaac Newton ( ) was able to find commonality in all things in the universe. He was very original in naming them the 1 st, 2 nd and 3 rd Laws of Motion. These laws describe the effects that forces have on objects.

2 Newton’s 1 st Law of Motion – Inertia INERTIA the tendency for an object to resist its change in motion. Basically, it wants to keep doing what it’s doing. 1 st Law states that… An object in motion tends to stay in motion, and an object at rest tends to stay at rest until another force acts upon that object. No mom, I don’t want to go!

3 Newton’s 1 st Law of Motion - Continued The book will stay there until (remain at rest) until another force moves it (the outside force). Think about it like this…the book is sitting on the table (it is at rest).

Newton’s 1 st Law of Motion - Continued Let’s look at a few examples of the 1 st Law of Motion in action! Another way to think about it is that the greater the mass of the object – the greater it’s inertia – the greater its’ resistance to move. Which wrestler would have the greatest inertia? Why?

5 Newton’s 2 nd Law of Motion - Acceleration 2 nd Law states that… a force acting on an object causes the object to accelerate in the direction of that force. When the golfer hits the ball, where is the ball going to go? Wherever they hit the ball, hopefully in the direction of the pin!

6 Let’s think about this one… if the Jorge kicks the soccer ball – which direction will the soccer ball go? Newton’s 2 nd Law of Motion - Continued Force causes acceleration of the object to accelerate in the direction of that force (the kicking of the ball).

7 Think about it like this… If the blue truck has a mass of 25,000kg and the red truck has a mass of 30,000kg which truck is going to take longer to speed up? Newton’s 2 nd Law of Motion - Continued Right, the RED Truck because it has a greater mass…5000kg more than the BLUE truck! Another way to look at the 2 nd law is that force causes acceleration. The greater the mass – the greater the resistance to acceleration.

8 Let’s look at a video of the 2 nd Law of Motion in action! Newton’s 2 nd Law of Motion - Continued

9 Newton’s 2 nd Law of Motion – The Formula Force = Mass X AccelerationF = ma Force units = kg.m/s 2 OR Newton F am divide multiply Mass units = kilograms (kg)Acceleration units = m/s 2

10 GUESS Read the problem, draw a picture and write down what is given in the problem. 15m/s kg Newton’s 2 nd Law of Motion – Calculations GUESS W rite down the unknown variables in the problem. What force is exerted on a 1000kg car accelerating at a speed of 15m/s 2 ? Problem: M = 1000kg Force A = 15m/s 2 GivenUnknownEquations NeededSubstitute including unitsSolution

11 Newton’s 2 nd Law of Motion – Calculations What force is exerted on a 1000kg car accelerating at a speed of 15m/s 2 ? Problem: GUESS W rite down the equation needed to solve the problem. M = 1000kg Force A = 15m/s 2 GivenUnknownEquations NeededSubstitute including unitsSolution F = maF = 1000kg x 15m/s 2 GUESS Substitute the known variables into the equation including the UNITS. F = 15,000 kg. m/s 2 OR F = 15,000 N GUESS Solve the equation including the UNITS.

12 Do problems 1-3 in your notes. Using all the correct steps!

13 Newton’s 2 nd Law of Motion – Gravity Any moving object being acted upon ONLY by the force of gravity is said to be "in a state of free fall” because these objects do not encounter air resistance. The acceleration for any object moving under the sole influence of gravity on Earth is 9.8m/s m/s 2

14 Newton’s 2 nd Law of Motion – Gravity Diagram Assuming that the position of a free-falling ball dropped from a position of rest is shown every 1 second, the velocity of the ball shown to increases as the time increases. What relationship do you notice about the distance per every 1 second? So…what type of acceleration does the ball have? Positive or Negative.

15 Newton’s 2 nd Law of Motion – Gravity More on this later when we discuss potential and kinetic energy…. But for now, all you need to remember is that acceleration for any object moving under the sole influence of gravity on Earth is 9.8m/s 2.

16 Action / Reaction forces act in PAIRS. Newton’s 3 rd Law of Motion – Action/Reaction 3 rd Law states that… for every ACTION, there is an equal and opposite REACTION.

17 In this example, when the lady is walking, her feet push against the ground while the ground pushes against her feet. Thus action/reaction – pair is the feet and ground pushing off of one another. Newton’s 3 rd Law of Motion – Continued

18 Another example: Let’s think about this one…what are the pairs of forces that are acting against each other in order for the shuttle to launch? Newton’s 3rd Law of Motion - Continued Let’s look at how the 3 rd Law of Motion made the NASA affected the astronauts.

19 An increase in either mass or velocity causes an increase in momentum. Newton’s 2 nd Law of Motion – Momentum The property of a moving object due to both its mass and its velocity. For example, if both football players had the same mass of 95kg, but the one in the Yellow helmet was traveling at 10m/s and the one in the Orange helmet was traveling at 12m/s, would that make a difference? MOMENTUM Let’s find out…

20 Momentum = Mass X VelocityP = mv Newton’s 2 nd Law of Motion – Momentum Formula P vm divide multiply Momentum units = kg/m/s Mass units = kilograms (kg)Velocity or Speed units = m/s

21 Newton’s 2 nd Law – Momentum Calculations What is the momentum of the football players in the orange and yellow helmets? Which player has the greater momentum? Problem: Remember both players had the same mass of 95kg, but the one in the Yellow helmet was traveling at 10m/s and the one in the Orange helmet was traveling at 12m/s. G U E S S in order to solve the problem!

22 GUESS Read the problem, draw a picture and write down what is given in the problem. GUESS W rite down the unknown variables in the problem. Momentum GivenUnknownEquations NeededSubstitute including unitsSolution Newton’s 2 nd Law – Momentum Calculations V = 12m/s M = 95kg V = 10m/s M = 95kg V = 10m/s M = 95kg V = 12m/s M = 95kg Momentum

23 GUESS W rite down the equation needed to solve the problem. P = mv P = 95kg x 12m/s GUESS Substitute the known variables into the equation including the UNITS. GUESS Solve the equation including the UNITS. Newton’s 2 nd Law – Momentum Calculations Momentum GivenUnknownEquations NeededSubstitute including unitsSolution V = 10m/s M = 95kg V = 12m/s M = 95kg Momentum P = mv P = 95kg x 10m/s P = 1140 kg. m/s P = 950 kg. m/s

24 What is the momentum of the football players in the orange and yellow helmets? Which player has the greater momentum? Even though they had the same mass, did it make a difference that the orange player was traveling at a greater velocity in terms of momentum? Problem: Newton’s 2 nd Law – Momentum Calculations Back to our original questions… P = 1140 kg. m/sP = 950 kg. m/s Orange Absolutely!

25 Do problems 4 & 5 in your notes. Using all the correct steps!

26 In the examples given in your notes, identify if they are representing Newton’s 1 st, 2 nd or 3 rd Laws or multiple laws.