always limitations to the usefulness of the model, often they are the key to building a useful and productive model. From by Paul D’Alessandris A pole-vaulter, just before touching the cushion on she lands after a jump, is falling downward at a speed of 10 m/s. The pole-vaulter sinks about 2.0 m into the cushion before stopping. Motion Diagram Motion Information Event 1: The instant she Event 2: The instant she strikes the cushion. stops. t2 = t1 = 0 s r2 = -2.0 m r1 = 0 m v2 = 0 m/s v1 = -10 m/s a12 = Mathematical Analysis Now substitute this expression into the equation: Substitute this result back into the original equation: The driver of a car traveling at 16 m/s sees a truck 20 m ahead traveling at a constant speed of 12 m/s. The car starts without delay to accelerate at 4.0 m/s2 in an attempt to rear-end the truck. The truck driver is too busy talking on his cellular phone to notice the car. Motion Diagram Motion Information Car Object: Object: Event 1: Car begins 2: Collision! Event 1: Car begins Event 2: Collision! to accelerate. to accelerate. 0 s 0 s t1 = t2 = t1 = t2 = r1 = 0 m r2 = r1 = 20 m r2 =
always limitations to the usefulness of the model, often they are the key to building a useful and productive model. From by Paul D’Alessandris A pole-vaulter, just before touching the cushion on she lands after a jump, is falling downward at a speed of 10 m/s. The pole-vaulter sinks about 2.0 m into the cushion before stopping. Motion Diagram Motion Information Event 1: The instant she strikes the cushion. t1 = 0 s r1 = 0 m v1 = -10 m/s a12 = Event 2: The instant she stops. t2 = r2 = -2.0 m v2 = 0 m/s Mathematical Analysis Now substitute this expression into the equation: Substitute this result back into the original equation: The driver of a car traveling at 16 m/s sees a truck 20 m ahead traveling at a constant speed of 12 m/s. The car starts without delay to accelerate at 4.0 m/s2 in an attempt to rear-end the truck. The truck driver is too busy talking on his cellular phone to notice the car. Motion Diagram Motion Information Object: Car Object: Event 1: Car begins to accelerate. 2: Collision! Event 1: Car begins to accelerate. Event 2: Collision! t1 = 0 s r1 = 0 m t2 = r2 = t1 = 0 s r1 = 20 m t2 = r2 =