Physics make up lab: Flight Time/Projectile Motion
Part 1- Flight Time
1. This section will examine the behavior of a horizontally launched projectile in terms of its flight time by comparing its launch speed to its horizontal range. To investigate this, go to the website: http://www.physicslessons.com/iphysics.htm. Click on “Experiment 16 Projectile Motion.” Set the initial height to 1.5 meters. Set the initial speed to 1.0 m/s. Set the angle of inclination to 0 degrees (horizontal). Since mass does not affect the path of projectiles, leave it set at 1.0 kg. Launch the simulation and record the horizontal distance (displayed in red) for the first trial. For the remaining trials, vary the initial speed according to the data table and record the horizontal distances.
Initial Speed (m/s) / 1.0m/s / 1.5m/s / 2.0m/s / 2.5m/s / 3.0m/s / 3.5m/s / 4.0m/s / 4.5m/s / 5.0m/sHorizontal Distance (m)
2. On the axes below, create a Horizontal Distance (y-axis) vs. Initial Speed (x-axis) graph. Plot a line of best-fit taking into consideration that (0,0) is a data point.
Continue on next page.
3. Calculate the slope of the line by dividing the rise by the run similar to how you did it in the “Constant Motion” lab. Show your work below.
4. Since motion for projectiles is constant in the horizontal direction, the equation
Dx = vx t can be applied. Solve this equation for “t” below with just the variables.
t =
5. Since the rise of the line was “displacement” and the run was “horizontal velocity”, the slope was equal to the ______of flight for the projectile.
6. Calculate the time it takes a projectile to fall from a height of 1.5 meters using the equation Dy = viy t + ½ g t2. Don’t forget that it is launched horizontally, viy is zero! So, the equation becomes, Dy = ½ g t2. Hint solve the equation for “t” algebraically first, then plug in your variables to get an answer.
t=?
Dy=-1.5 m
g= -9.8 m/s2
7. Compare the answer to number 6 to your slope calculation in number 3 by calculating a percent error. Show your work and circle your answer.
Percent error = (Calculated time – time from slope) * 100%
Calculated time
Part 2 Predicting Horizontal Range
1. The purpose of this section is to accurately predict how far a horizontally launched projectile will travel in the horizontal direction. To do this, begin by resetting the simulation used in part 1 to model the lab performed in the classroom. Set the initial height to 0.88 meters (which is the height of the lab tables in class). Set the initial speed to 2.26 m/s (This values is a realistic number for the horizontal speed obtained in this lab). Set the angle of inclination to 0 degrees, which simulates a horizontal launch, and leave the mass at 1.0kg. Do not run the experiment yet. Calculate your prediction below first.
2. To begin our prediction, we first need to find how long the projectile will be in the air. Do this similar to step number 6 in part 1. Except this time, use -0.88 meters for Dy rather than -1.5 m. Show your work below and circle your answer.
3. Now that you have the time of flight, find range by using the equation for constant motion, Dx = vx t. Show your work and circle your answer.
Dx = ?
vx = 2.26 m/s
t = (your answer from #2)
4. Run the simulation now. Compare your predicted range from #3 to Horizontal Distance displayed in red on the simulation. Calculate a percent error showing your work.
Percent error = (Predicted range – Simulation range) * 100%
Simulation range
Part 3 Analysis/Conclusion Questions.
1. _____ For projectiles, horizontal motion is ______vertical motion.
A) dependent on
B) independent of
C) the same as
2. _____ For projectiles, horizontal motion is ______while ______occurs in the vertical direction.
A) constant, acceleration.
B) accelerated, constant motion
3. _____ T/F, Neglecting air resistance, a heavy projectile will fall faster than a lighter one.
4. _____ The slope of your horizontal range vs. horizontal velocity graph in part 1 was equal to the…
A) velocity.
B) range.
C) mass.
D) flight time.
5. _____ If air resistance were factored into the simulation for part 2, the horizontal range would be…
A) less than what was predicted.
B) more than what was predicted.
C) the same as the prediction. (no change)