Report

I. Motion- a change in position against a stationary background a. Speed 1. Describes how fast an object moves 2. Calculating speed : distance traveled / time it took to travel that distance 3. Calculated speed is always an average or instantaneous speed. D 4. Measured in m/s, or km/hr, or mi/hr, etc. S T Refers to objects that cover equal amounts of distance in equal amounts of time. Ex. A race car that has a constant speed of 96 m/s travels at a distance of 96m every second 1. Time always goes on the x-axis 2. Distance is always on the y-axis 3. Examples…… Moving fast Moving slow At rest Same as speed but includes direction -Ex. 45 mi/hr south Does not have to be a compass direction • Ex. 23 m/s towards third base Calculated the same way as speed Momentum o 1. Depends on an objects velocity and its mass 2. P = momentum 3. P= mass x velocity • Momentum Equation The SI unit for mass is kg. The SI unit for velocity is m/s. The SI unit for momentum is kg x m/s. 2000 kg • m/s west 500 kg •m/s east 1. Law of conservation of momentum : total momentum of two cars before a collision equals the momentum after the collision PRACTICE PROBLEMS : 1. Calculate the momentum of a 0.15 kg ball that is moving toward home plate at a velocity of 40m/s. 2. Which has greater momentum, a 2.0kg hockey puck moving east at 2.5m/s or a 1.3kg hockey puck moving south at 3.0m/s? 3. A track athlete throws a 2kg discus into a field with a velocity of 21m/s. What is the momentum of the discus? 4. Calculate the momentum of a 700g ball that is rolling down a ramp at 4.6m/s. 5. A cannon fires a 40.5kg shell toward a target and the shell moves with a velocity of 120m/s. Calculate the shell's momentum. Feeling pretty good about your abilities? Acceleration : A change in an object’s velocity. There are 2 ways an object can accelerate… 1. Change its speed 2. Change its direction Equation: a = final velocity –initial velocity time Acceleration Practice Problems PRACTICE PROBLEMS: 1. As a shuttle bus comes to a normal stop, it slows from 9.00m/s to 0.00m/s in 5.00s. Find the average acceleration of the bus. 2. During a race, a sprinter increases from 5.0 m/s to 7.5 m/s over a period of 1.25s. What is the sprinter’s average acceleration during this period? 3. A baby sitter pushing a stroller starts from rest and accelerates at a rate of 0.500m/s2. What is the velocity of the stroller after it has traveled for 4.75 minutes? • Practice Problems: Solving for Time Solving for Time: Marisa’s car accelerates at an average rate of 2.6m/s2. Calculate how long it takes her car to accelerate from 24.6m/s to 26.8m/s. If a rocket undergoes a constant total acceleration of 6.25m/s2, so that its speed increases from rest to about 750m/s, how long will it take for the rocket to reach 750m/s. A dog runs with an initial speed of 1.5m/s on a waxed floor. It slides to a stop with an acceleration of -0.35m/s2. How long does it take for the dog to come to a stop? Constant Velocity Speeding up Slowing down