Transcript Bellringer
Physics 1 Chapter 2 Friday, April 1, 2016 What is 34709 in scientific notation? How many seconds are in a Megasecond? How many seconds are in 1.2 years?(Put your answer in scientific notation) 3.4079 x 10 4 There are 1,000,000s in a Megasecond. There are 37843200s in 1.2 years or 3.78432 x 107 seconds Be able to identify the hypothesis, independent and dependent variables, control and sources of error in an experiment. Be able to calculate the average velocity of an object using the formula, V = D/T Convert 34years to seconds In the frisbee experiment, what was the independent variable? What axis should the dependent variable go on? Convert 34years to seconds ▪ 1072224000 seconds or 1.072224000 X 10^9 sec In the frisbee experiment, what was the independent variable? How far you were away from the target What axis should the dependent variable go on? ▪ The Y axis Know what force is Understand what it means for an object to be in mechanical equilibrium Know what vectors and scalars are Be able to draw vectors and add or subtract them What is force? Is force a vector quantity? Why? What does it mean to say that order doesn’t make a difference when adding or subtracting vectors? What is force? A force is a push or pull Is force a vector quantity? Why? Force is a vector quantity because it has both magnitude and direction. What does it mean to say that order doesn’t make a difference when adding or subtracting vectors? Vectors can be added or subtracted in any order and you still get the same answer. (Just like numbers) Know what a vector and resultant are Be able to draw vectors to scale on a graph and predict the resultant Be able to algebraically predict the resultant when adding or subtracting vectors If you leave your home and you walk 4 blocks west and 7 blocks North, how far are you away from home? If your scale on a graph is 1 cm = 5 miles and a line on the graph measures 3.9 cm, how far in miles is the line in the real world? What is a force? Forces cause a _________ in ________. If a drawing has a scale of 1cm = 10.5 miles. How long a line would you need on the drawing to represent a distance of 9 miles? What is a force? A push or a pull on an object. Forces cause a _________ in ________. Change, motion If a drawing has a scale of 1cm = 10.5 miles. How long a line would you need on the drawing to represent a distance of 9 miles? 1cm = 10.5 miles X 9 miles x = 0.86 cm Review contributions of Aristotle and Copernicus Be able to discuss the contributions of Galileo and Newton Be able to explain Newton’s First Law and why it is sometimes called the Law of Inertia Vocabulary: force, friction, inertia, mass, weight What is inertia? Using inertia, explain why when your books are on the seat of your car and you stop quickly, they may end up on the floor. What determines how much inertia an object has? Explain. What is inertia? Inertia is the tendency of an object to resist a change in its motion. Using inertia, explain why when your books are on the seat of your car and you stop quicly, they may end up on the floor. Inertia means that the books don’t want to change their motion as long as there isn’t a force on them. When the car stops, they keep moving forward What determines how much inertia an object has? Explain. The amount of mass an object has determines its inertia. The more mass, the more inertia!! Be able to discuss the difference between mass and weight Be able to calculate weight from mass and also to calculate mass from weight. Understand what affects the amount of mass in an object and what affects the amount of an object’s weight. Vocabulary: mass, weight, Newton What formula do you use to calculate weight, in Newtons? What is the difference between mass and weight? What does Newton’s First Law of Motion say? (Law of Inertia) What formula do you use to calculate weight, in Newtons? W = m * g, where g = 9.8m/s/s or 10 m/s/s What is the difference between mass and weight? Mass is the amount of matter in an object and does not change where weight is the force of gravity on an onbject and may change according to where you are. What does Newton’s First Law of Motion say? (Law of Inertia) An object in motion will stay in motion and an object at rest will stay at rest unless there is an unbalanced force. Understand that objects are already moving Be able to explain why all objects on earth are moving and give an example of this concept. For the activity we did last class, was there any difference between the sounds you heard when the nuts were spaced at different distances? If so, what was the difference? What do you think causes this difference? For the activity we did last class, was there any difference between the sounds you heard when the nuts were spaced at different distances? If so, what was the difference? The unequally spaced nuts should have had the same amount of time between each sound while the equally spaced nuts should have had unequal time intervals between the sounds. What do you think causes this difference? The nuts farther up on the string are being affected by gravity for a longer period of time and as a result are going faster then the rest. They do have to cover more distance but the increased speed makes them cover longer distance in the same amount of time. Understand that falling objects are accelerating at a constant rate. Be able to explain relative motion and give an example. Be able to solve problems using the equation for average velocity. Be able to explain the difference between speed and velocity. Vocabulary: relative motion, velocity, accleration What is the difference between velocity and speed? If you are on a plane traveling at 400 mph, what is your speed relative to the plane? Relative to the ground? If someone gets up and walks to the front of the plane at 8 mph what is their speed relative to the plane? Relative to an observer on the ground? If they now turn around and walk back to their seat, what is their speed relative to an observer on the ground? What is the difference between velocity and speed? Speed is the rate at which distance is changing while velocity is speed with direction. If you are on a plane traveling at 400 mph, what is your speed relative to the plane? Relative to the ground? A. 0 mph B. 400 mph If someone gets up and walks to the front of the plane at 8 mph what is their speed relative to the plane? Relative to an observer on the ground? A. 8 mph B. 408 mph If they now turn around and walk back to their seat, what is their speed relative to an observer on the ground? 392 mph Be able to interpret a distance versus time graph Understand that acceleration is any change in speed, direction or both and be able to give an example of acceleration Understand that acceleration can be negative or positive Calculate acceleration of an object using a = v/t What are three ways an object can accelerate? If an object has an acceleration of 5m/s2 and is accelerated for 3 seconds from rest, what is its final velocity? What does a negative slope on a velocity versus time graph mean? What are three ways an object can accelerate? Speed up, slow down, change direction(turn) If an object has an acceleration of 5m/s2 and is accelerated for 3 seconds from rest, what is its final velocity? Final Velocity = Initial Velocity + Accleration*Time Final Velocity = 0 + 5m/s2 * 3 seconds = 15 m/s What does a negative slope on a velocity versus time graph mean? It means that the object is slowing down. Be able to explain what free fall is and give an example. Be able to calculate the distance fallen by an object in free fall Be able to explain how air resistance affects objects in free fall Self Assessment: www.PHSchool.com Web code Csa-0400 Web code Csa-0300