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Summary

Physics - Projectile motion experiment...

Description

Projectile Motion Aim To perform an investigation, gather information and analyse data to calculate initial and final velocity, maximum height reached, range and time of flight of a projectile for a range of situations by using simulations, data loggers and computer analysis. Background Information Projectile motion can be considered as a motion in 2 dimensions, e.g a constant velocity horizontal motion, combined with a uniformly accelerated vertical motion. When an object on Earth is propelled into the air at a velocity where friction is negligible, if no other forces act, the object can be termed a projectile and it will travel in the familiar parabolic curving path characteristic of projectile motion. This projectile motion is produced because, while it is in flight, the only resultant force acting on the projectile is its weight. This results in the Earth’s gravity continually accelerating the projectile vertically down towards the surface while the horizontal motion is in the air, the vertical component of its vertical velocity is continually changing, while the horizontal component of its velocity remains constant. It is the 2 dimensional nature of a projectile that will be explored in this experiment. Equipment      

Projectile Launcher and Projectile Data-Logging System Motion Sensor Metre Ruler Aluminium Foil Table

Procedure Step 1 |

The projectile launcher was fixed at a height of 20 cm to the leg of a table, and an angle of 30 degrees to the horizontal.

Step 2 |

Ensuring there were no interferences from students or obstacles, the projectile was loaded into the launcher and fired.

Step 3 |

The students then placed aluminium foil around the projectiles approximate landing zone.

Step 4 |

The projectile was fired again and left an indentation on the aluminium foil.

Step 5 |

After it had been fired, students measured the distance of its launch using a metre ruler.

Step 6 |

The experiment was repeated three times with the same angle of launch, and the results obtained were averaged.

Step 7 |

The experiment was repeated using different angles of launch ( 30, 40, 45, 50, 60 )

Risk Assessment

Risk

Neutralisation

Heavy projectile could harm students when in motion

Projectile was handled safely, and students moved out of range of the projectile prior to launch

Results Angle of Launch

Range 1 (m)

Range 2 (m)

Range 3 (m)

Range Average (m)

30O

0.52

0.53

0.52

0.52

40O

0.67

0.60

0.63

0.65

45O

0.75

0.72

0.77

0.74

50O

0.65

0.62

0.64

0.64

60O

0.49

0.54

0.55

0.53

Discussion The results obtained from this practical aligned with Galileo’s Analysis of Projectile Motion, i.e. supported the constancy of the velocity of the horizontal component of projectile motion and the constancy of the acceleration of the vertical component. Experiment is valid as the angle of launch was carefully varied accordingly to measure the range of the projectile. The variables were kept controlled: -

Mass of projectile Height of projectile launcher Air resistance Force on propelled projectile

I removed any obstacles in the path of the projectile motion to ensure nothing interfered with the dependent variable (range) being measured. The experiment conducted indoors, minimised the air resistance and wind interference from outside (doors and windows closed). Although these precautions were taken air resistance still continues to be a major factor and can not be excluded completely and must be considered as a controlled variable in this first hand investigation. Other factors that may have cause an invalid result in the experiment is the height of the projectile launcher on the table leg and the type of projectile. To ensure accuracy, we used a metre ruler produced from a trustworthy source. This apparatus was used to measure the range of the projectile motion to the nearest centimetre. Furthermore, the accuracy has been uplifted as the projectile launcher had a built in protractor inside of it that could be used to adjust its angle of launch to the nearest degree. The experiment was reliable as it was repeated three times for each angle measured. The results obtained were consistent, ensuring the reliability of the experiment. Conculsion We have successfully conducted and experiment to measure the range of a projectile whilst varying the angle of launch by using data loggers, computer analysis and other equipment. Overall experiment was a valid endeavour....