Lab 1_ Describing motion (1)

LAB 1: Describing Motion Date 2/14/2024 Student’s Name Morgan Keefover Goals: • To understand how position, velocity, and acceleration are related. • To understand how to interpret the signed (+,–) of velocity and acceleration. • To understand how the acceleration of an object behaves when the direction of the object’s motion reverses. Theory: We use the following terms to describe motion: • position = the location of an object • instantaneous speed = how fast an object is moving at a particular instant in time • instantaneous velocity = how fast an object is moving at a particular instant in time as well as the direction of motion • acceleration = change in velocity over time We can also calculate the average values of an object’s velocity and acceleration in the following ways: v av = Change ∈ position ( ∆ x ) charge ∈ time ( ∆t ) = final position − initial position time intervel = x f − x i t f − t i Eq ( 1 ) The average velocity is the distance that an object travels divided by the time it requires to travel that distance and has units of m/s . a av = Change ∈ velocity ( ∆v ) charge ∈ time ( ∆t ) = finalvelocity − initial velocity time intervel = v f − v i t f − t i Eq ( 2 ) The average acceleration is the change in velocity divided by the time over which that change occurred and has units of m/s 2 . Page 1 of 9

Figure 1: Motion sensor Experiment In a real lab classes, several of the experiments in Physics 201 involve the use of sensors connected to a computer in order to obtain data. The combination of the sensors, computer interface box, and software was developed by Pasco Scientific and is known as Capstone. For this first experiment, in real lab classes, you would use a motion sensor (such as in figure 1) to produce graphs of position, velocity, and acceleration vs. time. The motion sensor uses ultrasonic pulses that reflects off of an object to determine its position. The velocity and acceleration of the object are obtained mathematically using formulas similar to those given in the Introduction. This technique is the same as taking a series of snapshots for the position of an object, taken at equal time intervals. By analyzing each snapshot, the reader should be able to analyze the motion of the object. Part 1: Position and velocity  Open the simulator 1: http://physics.bu.edu/~duffy/HTML5/motion_diagrams.html  Study the simulator to understand its functions.  Now set the following quantities for two cars by dragging the respective slider. Table 1: Car 1 and 2 settings on the simulator Car Position (m) Velocity (m/s) Acceleration (m/s 2 ) Car 1 (Red Car) 0 4 0 Car 2 (Blue car) 0 6 0  Run the simulator. Read the position of the cart using the simulator. Complete Table 2 and Table 3. 1. Calculate the velocity of the cars by using the equation v av = ∆x ∆t = Change ∈ position time Show a sample calculation and complete the data Table 2 and 3. [5 pts] Page 2 of 9

3. Using the position vs. time graph, find the velocity for each cart. Note that the slope of the position vs time graph represents the velocity of the object. [5 pts] Velocity of the Red Car = 8.0/2s = 4.0 m/s Velocity of the Blue Car = 12.0m/2s = 6.0 m/s Page 4 of 9 Insert the snapshot here.

Part 2: Velocity and acceleration  Now set the following quantities for two cars by dragging the slider. Table 5: Car 1 and 2 settings on the simulator Car Position (m) Velocity (m/s) Acceleration (m/s 2 ) Car 1 (red Car) 0 4 +0.3 Car 2 (Blue car) 0 6 +0.7  Run the simulator.  Notice that the simulator takes snapshots of the cars at every 2s. Mark the car positions on the motion diagrams as a color dot. Read the position data from the simulator and fill the data Table 6. 4. Now you may calculate the velocity of the cars by using the equation v av = Final position − initial position timeintervel = x f − x i t f − t i Show your calculation for the first 2s below and complete the velocity column on Table 6. [5 pts] 8.60m – 0m / 2s – 0s = 8.6m/2s = 4.3 m/s 18.40m – 8.60m / 4s – 2s = 4.9 m/s Table 6: Position and velocity for car 1 and 2 with respect to the time [5 pts] Time (s) Position of car 1 (m) Velocity of car 1 (m/s) Position of car 2 (m) Velocity of car 2 (m/s) 0 0 NA 0 NA 2 8.60 4.3 13.40 6.7 4 18.40 4.9 29.60 8.1 6 29.40 5.5 48.60 9.5 8 41.60 6.1 70.40 10.9 Page 5 of 9

Part 3: Position, Velocity and Acceleration • In a real lab, a cart was kept on an inclined track which attached to a motion sensor as is in the picture below. A student gave the cart a quick, moderate push upward, and allowed it to coast up the incline. Then, it was allowed to coast back down.  The graphs below show a single trip for the cart traveling up and then down the incline. Page 7 of 9

7. When the cart was moving uphill, what was the sign of the position, velocity and acceleration? [5 pts] Position: (+) Velocity: 0 Acceleration: (-) 8. When the cart was moving down the hill, what was the sign of the position, velocity and acceleration? [5 pts] Position: (-) Velocity: 0 Acceleration: (+) 9. Note the time when the cart was at the top of the incline. What is the velocity and acceleration of the cart at the top of the incline? Explain the possibility to have an acceleration when its velocity was zero? [5 pts] Time @ apex: 1.55 Velocity: 0 Acceleration: 0.2 m/s 2 Results and Conclusions (10 pts) Briefly summarize the objective of today’s lab as well as the results of your experiment. As the experiment was purely qualitative list two SPECIFIC concepts from lecture that the experiment demonstrated. Objective: The objective of today’s lab was to study the relationships between time, position, velocity, and acceleration. Results: We measured velocity of the car 1 (red car) to be 4.0 m/s . The set value is 4.0. This gives a percent error/difference of. 0 for our experiment. Concepts from the lecture: Page 8 of 9