5Unbalanced Forces Always cause a change in motion - Acceleration Acceleration – change in speed or direction of an objectStartingStoppingSpeeding upSlowing downTurning
6Net Force Combination of all forces acting on an object. Add forces working in the same direction.Subtract forces that are working in opposite directions.
7Vectors Lines with arrows that show force. Length of the line shows the amount of force (magnitude)The arrow shows the direction of the force.
8Add forces acting in the same direction 8 N + 6 N = 14 Newtons
9Subtract forces acting in opposite directions 20 N – 18 N = 2 Newtons
10Net Force = 0 Forces are balanced 20 N – 20 N = 0 NewtonsForces are balanced - No change in motion
11Net force and direction What is the net force?What direction are they moving?Why?
12Newton’s 1st Law of Motion Law of InertiaAn object at rest will stay at rest unless acted on by an unbalanced force.An object in motion will stay in motion at the same speed and direction unless acted on by an unbalanced force.
13In other words…An object will keep doing what it is doing unless forces become unbalancedAlso known as the “Law of Inertia”Inertia – An object’s tendency to resist change in motion.
15Vehicle RestraintsWhat is the purpose of vehicle restraints such as seat belts?Describe how Newton’s 1st Law of motion applies to vehicle restraints.
16Newton’s 2nd Law of Motion Law of AccelerationThe acceleration of an object by a force in inversely proportional to the mass of the object and directly proportional to the force applied.
17In other words…The smaller the object, the greater the acceleration AND the larger the object, the smaller the acceleration.The smaller the force applied, the smaller the acceleration AND the larger the force applied the larger the acceleration.
18Therefore Force = Mass X Acceleration Force = 1,000 kg X .05 m/s/s Force = 50 Newtons
19AccelerationThe rate of change in the velocity, speed and/or direction, of an object.Acceleration = Force/MassMeasured in meters/sec2
20Force = Mass X Acceleration If the amount of force stays the same and the mass of the object increases, what will happen to the amount of acceleration?If the amount of force stays the same and the mass of the object decreases what will happen to the amount of acceleration?
21What if the acceleration has to stay the same? What will have to happen to the amount of force needed if the mass of an object increases?What will happen to the amount of force needed if the mass of an object decreases?
22Spring Scales Used to measure force. Use the spring scale to measure the amount of force needed to pull the CPO car up the ramp with different amounts of weight/mass.What happens to the amount of force when the mass increases?
23Newton’s 3rd Law of Motion For every action, there is an equal but opposite reaction
24In other words… All forces act in pairs. When one object exerts a force on a second object, the second object exerts a force back that is equal in size but opposite in direction
27Speed/Velocity How fast an object is moving Rate at which an object covers a distanceSpeed = distance/time (meters/second)
28Calculating SpeedWhile on vacation, Lisa Carr traveled a total distance of 440 miles. Her trip took her 8 hours. What was her average speed?Speed = 440 miles/8 hoursAverage speed = 55 miles/hour
29Calculating Distance and Time Calculating the amount of time it takes to travel a distance.Time = distance/speedCalculating the distance traveled in a certain amount of time.Distance = speed X time
30What’s the difference between Speed and Velocity Velocity - The rate at which an object changes position. It’s the measurement of the rate and direction of motion.
31Force = Mass x Acceleration (F = MA) Which object would have the greatest force?A 500 g object accelerating at 10m/s2orA 10 g object accelerating at 10m/s2Use your formula chart to calculate ForceForce = Mass x acceleration
32Force = Mass x Acceleration 500g X 10 m/s2 = 5000 Newtons force10g X 10 m/s2 = 100 Newtons of forceThe 500g object exerts a greater force
33What is the motion of the object in the graph below?
34No motionMoving away fast at a constant speedStopped (no motion)Moving away more slowly at a constant speed
35What is the motion of the object in the graph below?
36Moving away at a constant speed Stopped moving (no motion)Accelerating
41Kinetic vs Potential Energy Kinetic Energy – Energy of motionThe faster you are travelling the more kinetic energy you havePotential Energy – Stored energyThe more stored energy you have built up the more potential energy you have
42Where does the rollercoaster have the greatest kinetic energy vs Where does the rollercoaster have the greatest kinetic energy vs. potential energy