Name__________________________________________ Date___________ Period______ PHYSICS U4 - 1 MOMENTUM & IMPULSE DIRECTIONS: SHOW ALL WORK USING G.U.E.S.S. DUE: Binder ROUND ANSWERS TO 2 DECIMAL PLACES. WRITE ANSWERS IN A COMPLETE SENTENCE IN CONTEXT OF THE PROBLEM. LATE: GRADE Momentum aka “mass in motion” Variable NOTES & PRAC Variable Symbol Units Momentum Definition & Picture Equation Impulse Variable Variable Symbol Units Impulse Definition & Picture Equation In football, the defensive player applies a force for a given amount of time to stop the momentum of the offensive player with the ball. Impulse- Momentum Theorem: Created by M. Kelly OBJECTS IN MOTION STAY IN MOTION! PRACTICE 1) A 2250 kg pickup truck has a velocity of 25 m/s to the east. What is the momentum of the truck? 2) The masses and speeds of four objects are given in the following table. Rank the objects in order of increasing magnitude of their momentum. Indicate ties where appropriate. Mass Speed Object A 10 kg 10 m/s Object B 15 kg 4 m/s Object C 5 kg 20 m/s Object D 60 kg 3 m/s 3) How does the momentum change if the mass of the object is doubled? 4) How is the direction of momentum related to the direction of velocity? 5) Former welterweight champion Ricky “The Hitman” Hatton had his punches officially measured on a punching bag that was hooked up to an accelerometer and a force sensor. His punches on average lasted .25 s and had an impulse measured at 980 N*s. How much force did Ricky hit the punching bag with? 6) A baseball player bunts (hits softly) a 0.144 kg baseball thrown at 43.0 m/s. If the bat exerts an average force of 6500 N on the ball for 0.00122 s, what is the final speed of the ball? Created by M. Kelly OBJECTS IN MOTION STAY IN MOTION! 7) A soccer ball has a momentum of 2.5 kg*m/s. You then apply and impulse of 10 N*s. What is the soccer ball’s final momentum? 8) A teenager who just started driving got into a car wreck when the car lost traction on a curve and struck a large tree. The crash happened at 26.8 m/s (60 mph). The teenager’s mass was 60 kg. a) If the teenager was wearing a seatbelt, then the teenager would come to a stop over a distance of about 2m in about 0.28 s. In this scenario, what is the amount of force that the seatbelt uses to stop the teenager with? b) If the teenager was not wearing a seatbelt, then the teenager would continue moving toward the dashboard at 26.8 m/s as the car hit the tree. As this happens, the car is still moving (crumpling up) at 9.9 m/s into the tree as the teenager makes contact with the windshield. The car “catches” the teenager in a time span of 0.02 s. Afterwards they both start moving together and come to rest. In this scenario, what is the amount of force that the windshield uses to slow the teenager down from 26.8 m/s to 9.9 m/s over the 0.02 second impact? c) Standing on the Earth at sea level you experience the acceleration due to gravity at 9.8 m/s2, that is referred to as 1 g-force. Most rollercoasters at amusement parks cause the riders to experience anywhere from 3.5 – 6.3 g-forces. This would mean that if you were standing on a scale and you experience a g-force of 5, then the scale would read your apparent weight as five times what it normally is. Fighter jet pilots experience between 9-12 g-forces. Death or serious injury will usually occur for any person if the gforces are greater than 25. Calculate how many g-forces the teenager experienced in both scenarios above and state the likelihood of survivability. Created by M. Kelly OBJECTS IN MOTION STAY IN MOTION! Independent Practice 9) A pitcher claims he can throw a 0.145 kg baseball with as much momentum as a speeding bullet. Assume that a .003 kg bullet moves at a speed of 1500 m/s. a) What is the momentum of a bullet? b) What must the baseball’s speed be if the pitcher’s claim is valid? 10) A 0.42 kg soccer ball is moving with a velocity of 12 m/s downfield. A player kicks the ball so that it has a final velocity of 18 m/s downfield. a) What impulse, or change in momentum, did the ball experience? b) Find the constant force exerted by the player’s foot on the ball if the two are in contact for 0.020 s. Created by M. Kelly OBJECTS IN MOTION STAY IN MOTION! 11) A 2500 kg car is slowed down uniformly from an initial velocity of 20.0 m/s to the north by a 6250 N braking force acting opposite the car’s motion. Use the impulse-momentum theorem to help answer the following questions: a) What is the car’s velocity after 2.50 s? b) How far does the car move during 2.50 s? c) How long does it take the car to come to a complete stop? 12) A 0.50 kg croquet ball is initially at rest on the grass. When the ball is struck with a croquet mallet, the average force exerted on the ball is 230 N. If the ball’s speed after being struck is 3.2 m/s, how long is was the mallet in contact with the ball? Created by M. Kelly OBJECTS IN MOTION STAY IN MOTION!