what is… displacement acceleration velocity projectile motion kinematics
Post on 18-Jan-2016
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ProfessionsDan Hill (BASc)Production & Development Engineer
What I do: Responsible for all aspects of production of carbon fibre reinforced plastic structural components - the skeleton of the plane
Best part of job: It requires a broad set of skills ranging from chemistry, applied mechanics, tooling/machine design, process optimization, economics etc.
ProfessionsAndre Droste (BASc)Field Service Engineer
What I do: Work with large mining equipment (shovels, drills, trucks)!
Best part of job: I get to troubleshoot equipment problems in the field and have to think on my own feet!
Learning ObjectivesAt the end of this lesson, you will be able to
Perform simple experiments to show that vertical and horizontal components are independent in projectile motion
Predict whether particular projectiles will collide with their targets when fired under different conditions
Design and perform experiments to test their hypotheses
Monkey and the Coconut
SummaryVertical and horizontal components are independent of each other
Quick poll to see if students remember
Displacement the vector quantity that defines the distance and direction between two positionsVelocity the vector measurement of the rate and direction of motion (change in position) of an objectAcceleration the rate of change of velocity as a function of time*The workshop will begin with a ball demo where students are asked to predict whether an object thrown horizontally will reach the ground first or after an identical object dropped from the same height. Students will try this out for themselves using the balls: drop the ball without moving their hand or drop the ball while moving their hand sideways. Another student will have to watch to see which ball reaches the ground first.
Balls that are dropped or thrown sideways from the same height will reach the ground at the same time. Ultimately, this will convey the principle that vertical and horizontal components are independent in projectile motion.*Take a look at the balls trajectories (path through space). The only force working on the ball once it leaves your hand is the force of gravity (ignoring air resistance). A ball with horizontal motion (with no initial vertical velocity) has the same vertical trajectory as a ball without horizontal motion. Vectors shown by blue arrows.*Everything that moves involves kinematics. This is especially evident in examples of projectiles: planes, rockets, bullets, balls in games etc.*I'm working at something not as cool as snowboards anymore (not skateboards or surfboards) but for an aerospace manufacturing company. We make structural components for the Boeing 787 Dreamliner - not as rad as boards, but way more complicated and challenging.Name: Dan HillMy degree is B.Sc. M.E. with Manufacturing Option.My job is Production & Development Engineer, responsible for all aspects of production of Carbon Fibre Reinforced Plastic structural components - the skeleton of the plane. It requires a very broad set of skills ranging from chemistry, applied mechanics, tooling & machine design, process optimization, and economics to name a few.***Students are asked to consider tossing a coconut at a monkey who drops from a tree at the instant the coconut is thrown and tries to catch the coconut. If the coconut is thrown directly at the monkey in the tree, one might expect it to go above the monkey since the monkey is falling. On the other hand, the coconut doesn't follow a straight line. Students are asked to hypothesize whether the coconut will hit the monkey or go above or below. Ask the students to draw simple plots (e.g. displacement over time) like the one they saw in the ball demo to show what they expect.
The monkey should catch the coconut since the distance fallen by the monkey and the coconut are precisely the same (neglecting air resistance) during the time the coconut is in flight.
The demonstration video hyperlinked by picture of Monkey and Coconut on the slide:http://www.youtube.com/watch?v=cxvsHNRXLjw&feature=related
Evaluate limitations of simulation: Students will be asked to speculate on possible limitations of each simulation e.g. the monkey will only catch the coconut if they are close enough so that the coconut can reach the monkey before it reaches the ground. The problem is slightly whimsical because the monkey is not likely to react instantly to the release of the coconut, and air resistance acts differently on the monkey and coconut. *Example plot diagram with animation.*Example plot diagram with animation: if coconut was fired at angle towards monkeys original position.Better video here: http://www.animations.physics.unsw.edu.au/jw/monkey_hunter.html*A small car which can be rolled across a table is equipped with a spring-loaded mechanism that propels a steel ball vertically upward. As the car rolls across the table, the string, which is attached securely to something on the table, becomes taut and pulls out a pin releasing the spring without significantly altering the velocity of the car. As it falls, the ball is caught by the car. The operation of the device is first explained to the audience, and the pin is pulled out while the car is at rest. Do not demo the car in motion otherwise students will already know that the car catches the ball!
Students are asked to hypothesize whether the car will catch the ball. Ask the students to draw simple plots (e.g. displacement over time) like the one they saw in the ball demo to show what they expect. What variable will they change to see if their hypothesis stays true over different conditions e.g. speed of the car?
Students will split into groups of 4 and each group will have their own apparatus.
Ask students to come up with some limitations of simulation e.g. theoretically, since the ball is launched from a car moving with a constant horizontal velocity, the ball has the same horizontal velocity as the car and thus remains directly above it, but other factors such as friction of the wheels and the possibly different air resistance of the ball and the car can cause the car to miss the ball. *Example plot diagram with animation.*Quick recap of what they learnt through the activities and applications in real life across different fields.*Everything that moves involves kinematics. This is especially evident in examples of projectiles: planes, rockets, bullets, balls in games etc.**