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Transcript

NEWTON’S LAWS LESSON: 4/19/05 1. The propeller pushes air backwards. The air pushes back on the propeller. A. Which of the forces shown above represents the air pushing back on the propeller? B. The thrust is the ___________ force and the _________ force is the air being forced backwards by the propeller. C. If the gravity ( weight) exactly matches the lift, will the airplane go up, down, or stay at the same altitude? _______________________________________________________. D. Which one of Newton’s three laws explains this statement, “if the propeller pushes air backwards then the air pushes back on the propeller with an equal force in the opposite direction.”? ________________ 2. A. What is the net force acting on each cart? Cart A__________ Cart B_____________ B. What is the total mass of each cart? Cart A__________ Cart B_____________ C. Calculate the acceleration of each cart (from f=ma we get a=f/m) Cart A__________ Cart B_____________ D. Explain what happens to the cart’s acceleration if the net force is kept constant and the mass of the cart is increased? E. Which of Newton’s three laws of motion explains what happens in D? 3. A. What is the acceleration of the cart in diagram A? _________m/s2 B. Suppose the mass of this cart remains the same and the net force is doubled. What effect will this have on the acceleration of the cart? C. Which of Newton’s three laws of motion explains your answer in B? NEWTON’S LAWS LESSON: 4/19/05 4. Refer to the diagram labeled “A”. If the cart is moving to the right at 3.0m/s, what will happen to the 10kg weight sitting on the top of the cart if the cart stops abruptly? 5. Look up Bernoulli’s Principle in your text. What is the significance of Bernoulli’s Principle with respect to an airplane? NEWTON’s Three Laws of Motion 1. Sometimes called the law of inertia. This law states: An object at rest will remain at rest and an object in motion will continue in motion at constant velocity, unless acted upon by a net force greater than 0N. 2. This law really states three things. Each is identified here by a superscript. This law, stated mathematically is F=ma 1A force acting on an object will cause the object to accelerate in the direction of the force, the 2acceleration being proportional to the force, and 3inversely proportional to the mass of the object. 3. This law is often referred to as the Law of Action and Reaction. Forces occur in pairs, equal in magnitude and opposite in direction. BERNOULLI’S PRINCIPLE Use the airfoil diagram to show ( Label) where: A. The air velocity is “high” and “low”. B. The pressure is “high” and “low”. C. The pressure is “high” and “low”. D. Label the weight vector and the lift vector, and the thrust and drag vectors. E. What is an airfoil? NEWTON’S LAWS LESSON: 4/19/05 INSTRUCTIONS FOR THE HYBRID PAPER AIRPLANE Step 1 Fold an 8 1/2 x 11 inch sheet of paper down the middle of the long dimension. Don't panic. Just look at the pictures. On the left I'll show you what you're starting with, and I'll mark (in blue) where you're going to fold. On the right you'll see what you should end up with after each step. Step 2 Next fold the two upper corners in at a 45degree angle. Be careful here to line these up, and do not let the flaps cross the middle of the paper. Use the middle fold as a guide. Step 3 Fold the upper point over and crease. Step 4 Next fold the new upper corners in at a 45-degree angle. Be careful here to line these up, and do not let the flaps cross the middle of the paper. Use the middle fold as a guide. Step 5 Undo step 4. (We need the creases for the next step) NEWTON’S LAWS LESSON: 4/19/05 Step 6 Using those creases as a guide, fold the corners as shown. What we are doing is building up an airfoil at the leading edge of the wing. Step 7 Using the edge of paper as a guide, fold the corners again, as shown. Step 8 Make the final fold for the wing leading edges. Step 9 Fold the tip over. Look closely at the drawing, don't fold too much, we just want to take the sharp edge off the nose. Step 10 Fold the plane in half. The angled lines below the picture show what the plane would look like from the back. Step 11 Fold the wing over to form the fuselage. Make the body nice and even. (You can see that it's even if the trailing edge of the wings makes a nice straight line) Step 12 Flip the plane over, and fold the other wing. NEWTON’S LAWS LESSON: 4/19/05 Step 13 Lay the plane out flat. Step 14 Fold the winglets as shown. Make them about 3/4 of an inch (About 20 mm). Project #1: BUILD A HELICOPTER 1. Cut the pattern out then cut down the center dotted line only as far as indicated tn the diagram above. You may want to write your name on your helicopter. 2. Fold the two “wings” outward in opposite directions as shown in the diagram below. Place a paperclip on the bottom of the helicopter as shown. NEWTON’S LAWS LESSON: 4/19/05 3. To fly the helicopter, either throw it upward paperclip end first OR you can drop it from some height…like off the Shark balcony HOW DOES THIS APPLE Y TO THE REAL WORLD? Maple Tree seeds are nature own helicopters! Here is a picture of Maple seeds as they come from the tree. These seeds twirl as the fall from the tree. This helps them disperse better in the environment. Question : Where does the leaf get it’s lift?