which of these are directly measuring in the projectile motion lab?
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Week 3 Lab Projectile Motion Google "PhET Projectile", it will be the first hit 1. Look at the "height" box at the top. What kinematics term does it actually stand for, and what point is it relative to? (hint: shoot the cannon once and watch the number closely). Explain your reasoning. 2. Fire the projectile launcher straight upwards (angle = 90°) at 23 m/s. Using kinematics, determine: a) the time it should take the projectile to reach maximum height. Show work. (Do the work by hand and then take a picture and paste below). Remember to show symbols first and then units and numbers. b) the maximum height reached by the projectile (Do the work by hand and then take a picture and paste below). Remember to show symbols first and then units and numbers. c) Now, using the measuring tape, measure the actual height reached by the projectile (remember to measure from the little plus sign at the base of the cannon). Copy and paste the image from the simulation into the space below showing the measurement. Was your answer to (b) the same as this measurement? If it wasn't, check your math over and find your mistake. 3. Pick any initial speed and launch angle, and try out firing all the different objects (golfball -> Buick). How does the mass of an object affect its motion through the air? Cut and paste two different images of two objects that you launched with the same speed and angle below. Also include your answer to the question.
Shaiju T.
Q6) Earlier I claimed that it didn't matter which object you used as a projectile, but that seems unlikely since we know that heavier objects will fall faster than lighter ones. Test whether the projectile motion is the same or different by doing a quick experiment. Explain what you did, what you observed, and your conclusion. Move to the "Vectors" section of the simulation, do a Reset to ensure we are starting with all the default settings. Turn Air Resistance off. Set your cannon to some height between 2 m and 10 m, with some launch angle between 20° and 70°, and an initial speed between 5 m/s and 20 m/s. Fire the cannon, if you don't like your choices (like the projectile goes off-screen), pick some different values. Q7) Based on the launch angle and initial speed, calculate the initial x and y components of the projectile. v0x = __________ v0y = __________ Note the tick marks along the projectile's path, these are positions every 0.1 seconds with the positions every 1 second indicated by open circles. [There is also a white circle indicating the very top of the trajectory and the final tick mark will likely be less than 0.1 seconds after the previous.] Use the TRH to collect Range and Height data along the trajectory at 0.5-second intervals. Fill in a table like the following, continue collecting data until you reach the end of the motion. H = __________ q = __________ v0 = __________ Time (t) Range (x) Height (y) 0.0 s 0.5 s 1.0 s ... Q8) Record the time, range, and height of the projectile at the top of its trajectory (white dot) and where it hit the ground. Q9) The range values are the horizontal or x positions of the projectile relative to the launch point. Based on how those positions were changing: (a) When was the x-velocity fastest? Slowest? (b) What can you say about the acceleration in the x direction? Q10) The height values are the y positions relative to the ground (how much above ground level at each moment). (a) When was the projectile moving upwards and when downwards? (b) Was there ever a moment when the y-velocity was zero? When? (c) Did the y-velocity stay constant (zero acceleration) or was it constantly changing? Now we'll check how your observations match up with the equations. Q11) For vertical motion under the influence of gravity without air resistance, we expect: vy = -g t + v0y. Show your work, you can check your answers against the answer to Q8. (a) Solve for the time when vy = 0 using 9.81 m/s^2 for g and using your answer from Q7 for v0y. (b) Find the height of the projectile at that time by putting numbers into the equation: y = -½ g t^2 + v0y t + y0 Q12) We know the projectile hits the ground when its y-position equals zero. Use the equation y = -½ g t^2 + v0y t + y0 to solve for the time when the projectile hits the ground. Show all your work, again your answer should agree with the answer in Q8. [Hints: Use y = 0, g = 9.81, v0y from Q7, y0 = cannon height = H; you will have to solve a quadratic equation.]
Morgan C.
Introduction: Recall that a projectile is an object that is launched (projected) with some velocity into the air and subsequently moves under the influence of gravity. In this laboratory, you will investigate several aspects of such motion. In the following, you can discuss your ideas with other people but should break up into groups of two to prepare the report. 1) Consider the following problem: Suppose you shoot a cannonball (launcher) straight up into the air and are able to measure the height H it attains. Explain how you would utilize this information to determine the speed that the ball leaves the cannon. Develop the equation. Now, for the following data, determine the velocity of the ball as it leaves the cannon (launcher). Given your uncertainty in H, estimate your uncertainty in the speed ΔV. H = 1.06 m ΔH = V = ΔV =
Ivan K.
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