* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download forces
Survey
Document related concepts
Modified Newtonian dynamics wikipedia , lookup
Classical mechanics wikipedia , lookup
Fictitious force wikipedia , lookup
Newton's theorem of revolving orbits wikipedia , lookup
Rigid body dynamics wikipedia , lookup
Relativistic mechanics wikipedia , lookup
Fundamental interaction wikipedia , lookup
Centrifugal force wikipedia , lookup
Centripetal force wikipedia , lookup
Center of mass wikipedia , lookup
Classical central-force problem wikipedia , lookup
Newton's laws of motion wikipedia , lookup
Transcript
UNIT 2 FORCES IN ACTION MACHINES MOVE THE WORLD L3 L4 L5 L6 Marta Vidal Vidal ISAAC NEWTON (1642-1727) FIRST LAW OF MOTION. INERTIA An object at rest stays at rest, an object in motion stays in motion. Why does an object stop its motion? Why do objects change its direction? Because it is the result of an UNBALANCED FORCE applied upon an object. Unbalanced force Start motion Stop motion Change direction Change shape Balanced force • No change • No visible effect WHICH FORCES INFLUENCE MOTION? Contact forces FORCE is any influence that causes Friction a free body to undergo a change in Push/Pull speed, a change in direction, or a change in shape. Weight Non-contact forces Gravity Magnetism superconducting HANDS ON! Friction PROBLEM: How do different surfaces affect the movement of the objects? MATERIALS: Pencil, toy car, metric tape, 4 clothespegs, tape, scissors, aluminium foil, wax paper, recycled paper, sand paper, a calculator and plastic cable covers. STEPS: 1. Predict the distance of the toy car on each surface. 2. Create a ramp using 4 clothespegs and plastic cable covers. 3. Drop the toy car and measure the distance. 4. Do 3 different trials for each surface and calculate total distance. Play with friction HANDS ON! Friction PROBLEM: How do different surfaces affect the movement of the objects? STEPS: 1. Predict the distance of the toy car on each surface. SURFACE PREDICTION cm TRIAL 1 cm TRIAL 2 cm TRIAL 3 cm DISTANCE T1+T2+T3 3 Aluminium foil cm Wax paper cm Recycled paper cm Sand paper cm HANDS ON! Friction PROBLEM: How do different surfaces affect the movement of the objects? STEPS: 2. Create a ramp using 4 clothespegs and plastic cable covers. HANDS ON! Friction PROBLEM: How do different surfaces affect the movement of the objects? STEPS: 3. Drop the toy car and measure the distance. 4. Do 3 different trials for each surface and calculate the total distance. Total distance = trial 1 + trial 2 + trial 3 3 SURFACE PREDICTION cm TRIAL 1 cm TRIAL 2 cm TRIAL 3 cm DISTANCE T1+T2+T3 3 Aluminium foil cm Wax paper cm Recycled paper cm Sand paper cm WEIGHT ENGLISH DECIMALS IS IN . (DOT) SPANISH DECIMALS IS IN , (COMMA) MASS is a measurement of how much matter is in an object. WEIGHT is a measurement of how hard gravity is pulling on that object. On Earth 1 kg of mass = 9.8 newtons Gravity on Earth is 1G = 9.8 newtons WEIGHT = MASS x GRAVITY WEIGHT = 1kg x 1 1 WEIGHT = 1 Kg or is = 9.8 newtons On Earth our mass is equal to our weight. MASS = 1kg WEIGHT= 1kg Our MASS is the same if What will happen to everywhere our weightbut if we we travel over the universe we have a travel around space? different WEIGHT MASS = 60 Kg WEIGHT = 60 Kg MASS = 60 Kg WEIGHT = 60 x 0.16 WEIGHT = 9.6 Kg Calculate your weight in the Solar System Look at the gravity of the planets, the sun and the Moon and calculate your weight in respect to those. Sun 27,90 Mercury 0,37 Venus 0,88 Earth 1,00 Mars 0,38 Jupiter 2,64 Saturn 1,15 Uranus 0,16 Neptune 1,22 Moon 0,16 your MASS your WEIGHT IS EQUAL TO GRAVITY MULTIPLIED BY Planets, Star and satellite Look at your results and underline the correct part of the sentence. Is it your weight different or is it equal? My weight never changes. changes. Is it your mass different or is it equal? My mass never changes. changes. Calculate your weight in newtons On Earth On the moon Weight = mass x gravity in newtons WEIGHT = ………. x 9,8 WEIGHT = ………. x 1,5 WEIGHT = ….....newtons WEIGHT = ….....newtons WHAT IS FORCE? It can be a PUSH or a PULL. OBJECT PUSH FORCE PULL FORCE Is it a push or a pull? ISAAC NEWTON (1642-1727) SECOND LAW OF MOTION. THE UNIT FOR THE FORCE IS IN NEWTONS The strength of a force is equal to the amount of the mass involved multiplied by any acceleration applied to it. F=mxa If the mass is bigger the effect of the FORCE is smaller F If the mass is smaller the effect of the FORCE is bigger F HANDS ON! Newtons MATERIALS: - Pencil - Tape measure - Weighing scale - Dynamometer - 3 objects. PROBLEM: How do you use a dynamometer? What is the relationship between mass and force? STEPS: 1. Predict the power of the force needed to move the objects. Write a number from 1 to 3 (from bigger force to a smaller force). Objects PREDICTION MASS FORCE NEWTONS Result HANDS ON! Newtons MATERIALS: - Pencil - Tape measure - Weighing scale - Dynamometer - 3 objects. PROBLEM: How do you use a dynamometer? What is the relationship between mass and force? STEPS: 2. Measure the objects with a weighing scale and record it in your data table. Objects PREDICTION MASS FORCE NEWTONS Result HANDS ON! Newtons MATERIALS: - Pencil - Tape measure - Weighing scale - Dynamometer - 3 objects. PROBLEM: How do you use a dynamometer/spring scale? What is the relationship between mass and force? STEPS: 3. Put a tape measure on the floor and measure 100 cm in straight line. 4. Attach the object to the dynamometer and pull it along a distance of 100 cm and record the result in your data table. Objects PREDICTION MASS FORCE NEWTONS Result HANDS ON! Newtons MATERIALS: - Pencil - Tape measure - Weighing scale - Dynamometer - 3 objects. PROBLEM: How do you use a dynamometer? What is the relationship between mass and force? STEPS: 5. Write your conclusion about the experiment. 6. Share and check the results with the whole class. Write your CONCLUSIONS If the mass of an object is bigger smaller the force needed to move it is bigger smaller. If the mass of an object is bigger the force needed to move it is bigger. If the mass of an object is smaller the force needed to move it is smaller. ISAAC NEWTON (1642-1727) THIRD LAW OF MOTION ACTION AND REACTION All forces occur in pairs. For every action that takes place there is an equal and opposite reaction. FORCE CONTACT FORCES It is any influence that causes a free body to undergo a change in speed, a change in direction, or a change in shape. It is a force that acts at the point of contact between two objects. FRICTION It is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. PULL It is a force that can move something towards somebody/something. PUSH It is a force that can move something away from somebody/something. NON-CONTACT FORCES It is a force applied to an object by another body that is not in direct contact with it. MAGNETISM Force of attraction or repulsion acting between ferromagnetic materials like iron. GRAVITY It is a force that pulls all objects towards the center of the Earth.