Acceleration

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Harmony School of AdvancementPre-AP Physics

Raul RamosAcceleration is a measure of the rate at which the velocity of an object is changing. If you are riding in a car traveling in a straight line at a constant 50 kilometers per hour, you experience no acceleration because the car's velocity (rate of motion) is not changing. If the car begins to speed up, acceleration occurs because the car's velocity increases. If the car slows down, negative acceleration, or deceleration, occurs because the car's velocity decreases.

Table of ContentsI. Introduction................................................................................................3

A. Background Information and Research................................................3

B. Objective..............................................................................................3

C. Hypothesis...........................................................................................3

D. Variables..............................................................................................3

II. Materials.................................................................................................3

III. Procedures..............................................................................................3

IV. Data and Observations...........................................................................3

A. Observations........................................................................................3

B. Data.....................................................................................................3

V. Calculations.............................................................................................3

VI. Analysis...................................................................................................3

VII. Conclusion...............................................................................................3

VIII. Sources of Error....................................................................................3

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I. Introduction

A. Background Information and Research

If a cart moves on a plane that is inclined at an angle θ, the component of the gravitational force acting on the cart in a direction that is parallel to the surface of the plane is mgsinθ, where m is the mass of the cart and g is the acceleration due to gravity. The acceleration of the cart, in the absence of friction, should be gsinθ, both up and down the inclined plane. The acceleration is not expected to depend on the mass of the cart

B. Objective Determine what Deceleration means? What does Acceleration mean? What happens to the acceleration of a cart as it moves up

and down an inclined plane?

C. HypothesisAs the slope or steepness of the graph increases we would expect the acceleration to proportionally increase according to the vehicles total mass.

D. Variables

1. Independent: Slope of the graph

2. Dependent: Acceleration

3. Constants: Materials Example: Ramp, Vehicle, and Weights

II. MaterialsData Collection SystemDynamics TrackDynamics CartRod Stand

Motion SensorDynamics track Pivot ClampDynamics track End Stop

III. ProceduresSet Up:

1. Start new experiment on Data Collection2. Connect a Motion Sensor3. Display position on the y-axis of a graph with time of the x-axis4. Identify what the car does when acceleration is negative, but velocity is

positive.5. Set sampling rate to at least 20 samples per second6. Attach the stopper at the end of the ramp

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7. Mount the track to your rod stand using the pivot clamp8. Attach the motion sensor to the elevated end of the track.

Collect Data:1. Set the car at the top of the incline2. Approximately 15 cm from the motion sensor3. Start data collection and release the car.4. Catch the cart at the bottom of the inclined track just before it hits the end

stop and stop data collection5. Set the cart at the bottom of the incline6. Start data collection and give the cart a quick push up7. Allow the cart to roll back down the track and catch the cart at the bottom of

the inclined track just before it hits the end stop and stop data collection8. Sketch both runs on data in a graph.9. Use data collection to apply a linear fit to each run10. Save your data

IV. Analysis

1. During the period when the cart was in motion, are the Velocity versus Time graphs straight lines? Refer to the previous page if necessary. How is the acceleration of the cart changing fi our velocity versus Time graphs are straight lines?

2. Although the paths of the cart in both trials were different, the slopes of the velocity versus Time graphs for each trial are the same (during the period in which the cart was in motion.

3. Looking at the Velocity versus Time graph, what would a negative slope tell you about the cart’s acceleration? What would a positive slope tell you?

4. What was causing the cart to accelerate after releasing it from rest at the top of the track? Was that acceleration constant?

5. Describe the motion of an object that has a velocity versus time graph that is a horizontal straight line (a slope of zero).

Synthesis Questions:

1. The term “acceleration” is used in our everyday lives and language, but is often used in a non-physical context. Now that you have developed a physical definition of “acceleration,” give an example of where the physical definition matches the “everyday” definition. Given an example where they are different.

2. Modern aircraft carriers use a steam powered catapult system to launch jets from a very short range. These catapults can provide a constant acceleration to bring jets up to speed in only 2 seconds. If each jet requires a minimum take-off speed of 82.3 m/s, how much acceleration must the catapult supply so the jet can take off?

3. How many different devices in a car help to accelerate the vehicle? What are they?

Multiple Choice:

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1.V. Conclusion

The acceleration due to gravity was measured by timing a freely falling cart/ car. The value obtained from least squares fitting of the data yields .9 which is slightly higher than the accepted value. Given the potential for systematic error in the apparatus, this result is quite satisfactory and can be accounted for by the oddly shaped metal pad used to stop the elapsed time measurement. Despite our apparatus’s potential deviation we were able to note the overall change in velocity as steepness increased and mass. Both runs proved that velocity increased as the cart fell down, however, when the car was pushed up it gradually reached and optimum height, came to a sudden stop, and then accelerated down.

VI. Sources of ErrorPossible sources of error could have been:

Shifting the apparatusRough stops at the end of the trackMovement of the sensorEnvironmental shifts in motionHuman Error

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