Physics –Forces – The Glider Project Mystery (inertia) Stations (Newton’s 1st) Carts & Masses (Newton’s 2nd) Force Meters (Weight & Hooke’s Law) Student Experience Students visit various inertia demonstrations around room, and must determine what they all have in common (concept of inertia is not discussed until end of lesson). Students attach various masses to a string connected to a cart. The mass falls, students determine the acceleration of the cart, and discover the relationship between force, mass, and acceleration. Students create their own force meters using an elastic material (from the T4T cart) and calibrate them by hanging known masses. T4T Material Bowling ball, table tennis ball, pennies, tablecloth, dishes T4T cart, string, set of weights Elastic material from cart, vinyl window blind, set of weights Big Idea 1st Law. An object in motion will continue in motion with constant velocity unless acted upon by a net external force. Newton’s 2nd Law. Fnet = ma. Weight: Fg = mg Hooke’s Law: Fs = -kx (honors physics only) Connection to Culminating Activity The glider’s inertia causes its resistance to acceleration when launched. A net external force on an object will cause it to accelerate, which explains the glider’s acceleration during launch. The force meters are essentially scaled-down versions of the glider launcher that will be used in the culminating project. CA Standards PH1. b. PH1. c. -- Next Gen. Sci. Standards -- HS-PS2-1. -- Time One 55-min period Two 55-min periods One 55-min period CA Standards: PH1. b. Students know that when forces are balanced, no acceleration occurs; thus an object continues to move at a constant speed or stays at rest (Newton’s first law). PH1. c. Students know how to apply the law F = ma to solve one-dimensional motion problems that involve constant forces (Newton’s second law). PH1. d. Students know that when one object exerts a force on a second object, the second object always exerts a force of equal magnitude and in the opposite direction (Newton’s third law).
Tug-of-War (Newton’s 3rd) Force Stations (FBDs) Glider Engineering (Culminating Activity) Student Experience Students use their force meters to investigate systems where forces oppose each other. They predict force meter readings before testing. Students visit stations around the room and “draw the forces.” Then, FBDs are introduced, and students create correct FBDs for each system. Students create a glider to be launched by a rubber band or gravity-driven launcher. The glider must achieve a minimum launch velocity, but avoid too great an acceleration (so the “pilot” doesn’t black-out). If using rubber band, teacher provides students with average force exerted by the launcher. Material Student-made force meters. T4T cart materials, simple machines. T4T cart materials Big Idea Newton’s 3rd Law. FA,B = –FB,A Free-body diagrams help depict the forces acting on a system. Fnet = ma v2 = v02 + 2a∆x Connection to Culminating Activity -- Students will create a FBD of the glider-catapult system. -- CA Standards PH1. d. -- -- Next Gen. Sci. Standards -- -- HS-PS2-1 Time One 55-min period One 55-min period Five to eight 55-min periods Activity Guide for Forces Unit Prior Knowledge: Students know how to solve problems that involve constant speed and average speed. (v = ∆x/∆t) Students know how to solve problems that involve constant acceleration and average acceleration (a = ∆v/∆t) Students know how to solve for the acceleration a of an object starting at rest (v0 = 0) and traveling a given distance ∆x for an amount of time t. (Use ∆x = v0t + ½ at2.) Students know how to solve for the final velocity v of an object starting at rest (v0 = 0) and undergoing a constant acceleration a for a distance ∆x. (Use v2 = v02 + 2a∆x.) Students know that a gravity will accelerate a falling object at 9.8 m/s2 .
Area evaluated: Description Glider Design The glider is designed so that at least one aspect of it can be easily varied for the purpose of the experiments. The glider is sturdy and will survive multiple flights. (10) The glider’s construction is questionable or of low quality. It is not immediately apparent which aspect of the glider can be varied for the experiments. (5) The glider is poorly constructed, with no consideration for variable design features. (1) Launch & Flight Performance The glider successfully launches from the catapult, and flies through the air. (10) The glider launches from the catapult, but does not fly–rather it falls abruptly. (5) The glider cannot be launched and it does not fly. (1) Questions The design questions are addressed with high-quality responses that demonstrate critical thinking and an understanding of cause & effect. (10) There is insufficient justification for the glider’s design. There is little evidence that the experiment influenced design considerations. (5) The experiment was invalid, or the responses to the questions are of low quality. (1) Questions The physics presented in the analysis is correct, neat, organized, and includes correct units. (10) The physics analysis is mostly correct, but has a few mistakes. The presentation is messy or disorganized. (5) The physics analysis is mostly incorrect. The presentation of the work is of very poor quality. (1) Competition Bonus 1st Place in class (5 bonus) 2nd Place in class (3 bonus) 3rd Place in class (1 bonus)