Experiment 2 Squeeze Rocket Projectiles In this experiment you will investigate how the launch angle of a projectile affects the distance it travels Materials Masking Tape Mirror Support Printer Paper Protractor 4 Squeeze Rockets 1 Squeeze Rocket Bulb Stopwatch Tape Measure Pencil Procedure 1 Place the unused side of the printer paper face up on a flat work space and secure with a piece of masking tape 2 Use a pencil to mark the spot in the middle of the printer paper This is the where the rockets will be launched every trial 3 Stabilize a protractor so that it stands up vertically by inserting the flat part of the protractor into the mirror support Using a protractor align the rocket to a 90 angle In other words it should be vertically directed upward 4 Load a Squeeze Rocket onto the bulb Note The Squeeze Rocket is a trademarked product name The rocket itself does not use a selfpropelled mechanism After the Squeeze Rocket is launched gravity is the only major force which acts upon the rocket 5 Predict how far you believe the rocket will be propelled from its original position if you squeeze the bulb Record your prediction in Table 5 6 Squeeze the bulb you will need to replicate the same pressure for each trial and simultaneously start the stopwatch upon launch Measure and record the total time the rocket is in the air Repeat this step three more times and average your results Record all data in Table 5 Note You may wish to include a partner for this step to work the stopwatch 7 Calculate the launch velocity of the rocket using the kinematics equations Record your calculation in Table 5 Hint You can take the initial height as zero The vertical velocity is zero at the peak of the flight when the time is equal to t 2 2014 eScience Labs LLC All Rights Reserved 8 Choose three new angles from which to launch the rocket Record the angles you select in Table 5 9 Before launching the rocket use the following equation to calculate the expected range using the launch velocity and the angle from which the rockets will be fired R v2 sin 2 g Remember that you can use zero for any initial positions and that the acceleration due to gravity g is 9 8 m s2 Record the expected ranges in Table 5 10 Next align the rocket with the first angle choice and fire it with the same force you used initially Squeeze the bulb and measure the distance traveled with the tape measure Record the distance propelled for four separate trials at this angle Then average the four trials and record in Table 5 Note Try to record launches where the rocket travels in a parabola and does not stall or flutter at the top 11 Repeat Step 9 10 for your remaining angles Record all data in Table 5 12 Record the percent error between your calculated and actual values in the last column Percent error observed value expected value x 100 expected value Table 5 Projectile Data for Rockets with Different Launch Angles Launch Velocity m s Average Predicted Time s Time s Range m Initial Angle 1 8 90 1 23 90 1 75 90 1 92 90 Actual Range m Average Range Range m Error 0 0 0 0 0 0 1 68 0 0 0 45 1 38 3 23 1 75 84 57 45 1 93 3 23 2 46 45 1 74 3 23 2 21 45 1 53 3 23 1 95 30 1 48 2 842 1 332 1 645 1 645 1 573 2014 eScience Labs LLC All Rights Reserved 0 0 2 093 0 0 31 30 46 15 65 64 1 4153 53 13 30 1 69 2 842 1 521 86 86 30 1 77 2 842 1 593 78 40 30 1 35 2 842 1 215 57 23 25 1 63 0 25 1 24 79 59 25 1 32 0 25 1 00 25 1 79 0 25 1 36 25 1 30 0 25 0 936 1 510 1 147 75 00 81 62 74 94 Post Lab Questions 1 Which angle provides the greatest range Which provides the least Based on your results which angle should give the greatest range for projectile motion 45 degrees gives the greatest range 90 degrees gives the shortest range of zero 2 What role does air resistance play in affecting your data Air resistance reduces the effective range 3 Discuss any additional sources of error and suggest how these errors could be reduced if you were to redesign the experiment setting of theprojectile launcher affects the set angle after each launch The launcher should be held in a fiexedv angle fixture 4 How could kickers on a football team use their knowledge of physics to better their game List at least two other examples in sports or other applications where this information would be important or useful The kickers should apply physics to try and kick the ball at 45 degrees so that it goes for the furthest distance This information could also be used in athletics to throw javeline The military could also apply the concept of projectiles to aim a target using missiles or guns 2014 eScience Labs LLC All Rights Reserved
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