Kinematics 1-D Online (1)

P h y s i c s L a b 1 ( O n l i n e S i m u l a t i o n ) KINEMATICS IN ONE DIMENSION Mechanics Unit 1 TA name: Lotfihagh, Awat Due Date: Febuary 8 2023 11:59 PM Student Name: Sribhav Danthala Student ID: 1002128648 Simulation created by the Physics Education Technology Project (PhET) The University of Colorado at Boulder Go to: https://archive.cnx.org/specials/e2ca52af-8c6b-450e-ac2f-9300b38e8739/moving-man/ Investigating Motion: Distance, Velocity, and Acceleration through Time 1

P h y s i c s L a b 1 ( O n l i n e S i m u l a t i o n ) Objective: This activity is intended to enhance your physics education. We offer it as a virtual lab online. We think it will help you make connections between predictions and conclusions, concepts and actions, equations and practical activities. We also think that if you give this activity a chance, it will be fun! This is an opportunity to learn a great deal. Answer all questions as you follow the procedure in running the simulation. Learn about position, velocity, and acceleration graphs. Move the little man back and forth with the mouse and plot his motion. Set the position, velocity, or acceleration and let the simulation move the man for you. Introduction: Kinematics is a part of mechanics dealing with mathematical description of motion. It does not concern the causes of the motion or change in motion. Kinematics equations describe motion using variable quantities like position, velocity, acceleration, and time. The following basic kinematics equations are used to model one dimensional motion: x = x 0 + v ( t − t 0 ) v = v 0 + a ( t − t 0 ) v 2 = v 0 2 + 2 a ( x − x 0 ) x = x 0 + v 0 ( t − t 0 ) + 1 2 a ( t − t 0 ) 2 Where all quantities with subscript “0” are initials and quantities with “_” on top of letters are averages. In this simulation, you will learn how the graphs represent the motion of the moving man and use data from the graphs to solve equations that can be used to predict the motion of the moving man. Procedure: 1. Open The Moving Man https://archive.cnx.org/specials/e2ca52af-8c6b-450e-ac2f-9300b38e8739/moving-man/ 2. Take five minutes to play; move the man with your mouse and observe the three graphs. Set some values. Have fun. You can type exact values into the magnitude boxes. 3. Clear the graphs between runs with the button. 4. Set the man’s velocity to 2m/s, the position at -10m, and acceleration remains at 0 m/s 2 . Click the play button and observe all graphs for 10 seconds. a. What is the position at t=3s (the initial position)? x 0 =-4m b. What is the position at t=4s (the final position)? x=-2m c. Calculate the average velocity for an elapsed time. 2

P h y s i c s L a b 1 ( O n l i n e S i m u l a t i o n ) v(at 3s)=-3m/s, v(at 9s)=3m/s f. Turn on the vectors and observe how the directions of the vectors behave. Did you see the change in direction with the velocity, acceleration or both? Explain I saw a difference in velocity since he changed direction it went from negative -3 to 3 since he was going from the other direction compared to the last question g. Calculate the velocity at t=6s. What is the physical meaning of your result? v=0m/s The object has stopped momentarily and will change directions h. Write the quadratic equation which represents the position vs. time graph you obtained X=-9+6t-1/2t^2 7. Explain how the position, velocity, and acceleration graphs of question 4 are different from the same graphs of question 5. Hint: compare same type of graphs, for example position with position. The position, velocity, and acceleration graphs of question 4 and question 5 differ due to changes in the initial conditions of the moving man. In question 4 the initial position is at -10m and the man moves with a positive velocity of 6m/s and negative acceleration of -1.0m/s^2, resulting in a graph that curves downward. In question 5 the initial position is at 9m and the man moves with a graph that moves upwards. 8. To get the man to stop at home starting from a tree, I set the velocity to 0m/s and acceleration to 1.0m/s^2 9. Try to reproduce the position vs. time graph shown below and draw the corresponding Velocity vs. time and acceleration vs. time graphs. 4

P h y s i c s L a b 1 ( O n l i n e S i m u l a t i o n ) 10. Remove the walls (click on “x” sign on walls and setup this scenario: a. A car travelling 5m/s slams on its brakes, creating an acceleration of -2m/s 2 . How far did the car travel after it applied its brakes? x =-3.75m. b. How long does it take for the same car to stop? t =2.5s. Follow up questions: 1. When velocity and acceleration have the same sign, the object is (a) not moving (b) speeding up (c) slowing down - the object is (b) speeding up. If velocity and acceleration have the same sign, it means they are acting in the same direction. This causes the object to accelerate, either increasing its speed if both are positive or decreasing its speed if both are negative. 2. When velocity and acceleration have the opposite sign, the object is (a) not moving (b) speeding up (c) slowing down - The object is (c) slowing down. If velocity and acceleration have opposite signs, it means they are acting in opposite directions. This causes the object to decelerate, or slow down, as the acceleration opposes the motion indicated by the velocity. 3. Consider the braking car. When the speed was doubled, the distance to a stop was (a) less than double (b) double (c) more than double 5

P h y s i c s L a b 1 ( O n l i n e S i m u l a t i o n ) influenced by the initial velocity, as a higher initial velocity will result in the need to dissipate more kinetic energy, requiring a longer braking distance. 7