Physics Laboratory 3

Projectile motion

Projectile motion is motion in two dimensions under the influence of a constant force.  An object moving through the air near the surface of the earth is subject to the constant gravitational acceleration g, directed downward.  If no other forces are acting on the object, i.e. if the object does not have a propulsion system and we neglect air resistance, then the motion of the object is projectile motion.
In this lab you will analyze the motion of a ball executing projectile motion.

Open a Microsoft Word document to keep a log of your experimental procedures and your results.  This log will form the basis of your lab report.  Address the points highlighted in blue.  Answer all questions.

Exercise

The New York Giants are tied with the Chicago Bears with only a few seconds left in the game.  The Giants have the football and call the place kicker into the game.  He must kick the ball 52 yards (47.5 m) for a field goal. 

If the crossbar of the goal is 10 ft (3.05 m) high, and the maximum speed with which the kicker can kick the ball is 25 m/s, which range of angles (in deg) will allow him to score the field goal?

Solve this problem using a spreadsheet.  Produce a spreadsheet with 5 columns.

v0 (m/s) Angle (deg) t (s) x (m) y(m)

Hint:  Download this spreadsheet to get started.

The first two columns each contain one entry each.  Construct your spreadsheet so that when you change these numbers, the numbers in the next three columns will be updated.  The time steps in the t(s) column should be on the order of 0.1 s or smaller.  The entries in the x(m) and y(m) columns are calculated as a function of time using the kinematic equations.

In one full sentence answer the question above.


Experiment

A ball is moving in two dimensions under the influence of a constant gravitational force.  It is hard to get detailed information about its motion without using external measuring instruments.  In this experiment the instrument is a video camera.  You will analyze a video clip.  The clip shows a ball being thrown.  You will determine the position of the ball in two dimensions as a function of time by stepping through the video clip frame-by-frame and by reading the time and the position coordinates of the ball off each frame.  You will construct a spreadsheet with columns for time and position and use this spreadsheet to find the x and y component of the velocity as a function of time.

Procedure:

To play the video clip or to step through it frame-by-frame click the "Begin" button.

Produce graphs of the x and y components of position versus time.  Label the axes.

Paste your graphs with trendlines into your log.


Activity

In this virtual laboratory you will investigate projectile motion with and without air resistance.  You will find the maximum range of a baseball with given initial velocity and the launch angles required for it to hit a target.

Procedure:

Open the Projectile Motion simulation.  Click "Intro".

Position the canon 20 m to the left of the target.  Make sure the cross on the canon is at the same height as the target.  Choose the baseball projectile and give it an initial speed of 20 m/s.

Projectile speed: 20 m/s
  Maximum range Launch angle (deg) Maximum height (m) Hang time (s)
no air resistance        
drag coefficient 0.35        

Convert your log into a lab report.

Name:
E-mail address:

Laboratory 3 Report

Save your Word document (your name_lab3.docx), go to Canvas, Assignments, Lab 3, and submit your document.