Senior School Science Physics

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Education@Gumbuya

Senior School Science Physics

Welcome to Gumbuya World’s Senior School Physics Program.

During the program, students will give both qualitative and quantitative explanations of the relationships between distance, speed, acceleration, mass and force to predict and explain motion. They will use the concepts of voltage and current to explain the operation of electric circuits.

They will also be able to explain the concept of energy conservation and model energy transfer from kinetic to potential and back again, and transformation within systems.

Students will apply the knowledge gained from the theory component to the practical component of the session whilst experiencing the rides first hand. Students will feel free-fall sensation, transfer of energy states, potential to kinetic and back again, randomised banking turns, single continuous banking corning, differences in speeds and side to side motion. Students will also be given the opportunity to develop and communicate scientific ideas and information, including constructing evidence-based arguments and using appropriate scientific language, conventions and representations.

The following worksheet questions are aimed at a variety of year levels, ranging from Year 7 through to early VCE and serve to supplement classroom resources and real-world experiences.

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Desert Derby Dodgem Cars

Purpose

To investigate the acceleration, forces and impulse experienced during a typical ride in a dodgem car.

To review basic electrical circuits powering a dodgem car, including DC and AC circuitry.

Momentum is a physics concept demonstrated well by using dodgem cars. The more

momentum that an object has, the harder that it is to stop. A greater amount of force, a longer amount of time or both will be needed to stop the object. As the force acts upon the object for a given amount of time, the object's velocity is changed; and hence, the object's momentum is changed.

These ideas come from Newton's second law. Newton's second law states that the acceleration of an object is directly proportional to the net force acting upon the object and inversely

proportional to the mass of the object. Combined with the definition of acceleration (𝑎 =Δ𝑣

𝑡),

then:

𝐹 = 𝑚 x 𝑎 or 𝐹 = 𝑚 x Δ𝑣_𝑡

Force, acceleration and velocity are all vector quantities, so both the magnitude (or amount) and the direction matter.

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Q1 – Observing Impacts and their Results

Either while waiting for your turn on a dodgem car or following your ride, sit back in the observation area alongside the track and watch some of the collisions. For each of the types of collisions below, circle the appropriate set of arrows to indicate which direction the cars and riders move immediately after impact. Assume the masses of drivers A and B are equal.

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Q2 – Unbalanced Masses

Using the information above, explain through observation or other means how changing the impacts to be unbalanced by having a larger mass in one car than the other, could change the resulting directions and velocities

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Gumbuya’s Dodgem Cars are powered by a floor-mounted electrical panels, with each panel connected in series along each row, and each row connected in parallel. Both alternating

current (AC) and direct current (DC) circuits are used, with transformers and rectifiers to change between the types at different locations.

Q3 – Series / Parallel Circuits

Draw a simple diagram showing the Dodgem Car floor circuit, including the series and parallel panels.

Describe the difference between the two types of circuits.

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Q4 – Types of Current

Desert Derby’s cars are powered by Direct Current via the floor panelling. Explain the difference between DC and AC

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Describe how the Dodgem’s Main Power Supply would change the voltage from mains supply of 415 volts to the required 48 volts for the floor

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Extension: Each dodgem car has a DC motor drawing 12 Amps when powered. Knowing that Power = Voltage x Current (P=VI), if there are 10 cars running, how much power does the ride controls need to provide to the floor for all cars to move?

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Assuming no power is lost during transforming, how much current does the ride controls need from mains power supply?

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Mining Race Coaster

Purpose

To investigate the acceleration and motion experience on the Mining Race roller coaster. To better understand the changes in energy states

Q1 – Average Velocity

While observing the ride from outside the fence, use a stopwatch or similar to measure the time it takes the roller coaster to complete three laps of the track.

seconds

Knowing that the track length is 130 metres long, show with working the average velocity of the roller coaster for a single lap of the track.

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Why would we record the time taken for three laps, instead of a single lap?

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Q2 – Force and Acceleration

Using the diagrams below, show where you - Felt the heaviest

- Felt the lightest

- Felt the largest sideways force

Also, using a different coloured pen or marker, or a different symbol, show where the train was - The fastest

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Q3 – Conservation of Energy

Riders experience two main energy states on Race Coaster, being Kinetic Energy and Potential Energy

Calculate the maximum Gravitational Potential Energy at the coaster’s highest point of 6m, if the carriages and riders have a mass of 3250kgs.

𝐸𝑛𝑒𝑟𝑔𝑦_𝐺𝑃𝐸 = 𝑚𝑔ℎ

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Using the above result, calculate the maximum velocity the coaster can achieve, if friction is ignored. 𝐸𝑛𝑒𝑟𝑔𝑦_{𝐾𝑖𝑛𝑒𝑡𝑖𝑐} =1 2𝑚𝑣 2 ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

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Draw a rough sketch of the change of Potential Energy vs. Kinetic Energy below, for a single lap

Q4 – Energy Sources, Removal

Discuss as a group how the Race Coaster receives its energy and how this is transferred to the carriage train.

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The two main ways the Race Coaster removes energy from the carriage train is via magnetic braking, and electrically resistive braking.

Discuss as a group what this means and what form the energy ends up in. Discuss any other methods that energy is lost during the ride.

______________________________________________________________________________ ______________________________________________________________________________ 0 1 2 3 4 5 6 0 0.25 0.5 0.75 1 H eight (m) One Lap

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Rebel

Purpose

To investigate the acceleration and motion experience on the Rebel stationary pendulum. To investigate and discuss vertical circulation motion

Q1 – Force and Acceleration

Using the diagrams below, show where you - Felt the heaviest

- Felt the lightest

Also, using a different coloured pen or marker, or a different symbol, show where you were - The fastest

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Rebel can momentarily exert 7g’s of force on its riders. Describe what this means.

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Extension: Calculate how heavy a rider with a mass is 75kg would feel (effective weight) while experiencing 7g’s of force.

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Q2 – Vertical Circular Motion

While at maximum height of the circle, Rebel riders can come to a virtual stop. Describe why this is possible compared to a ‘ball on string’ vertical circle.

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If the ‘ball on string’ came to a stop at the top of the circle, what would occur?

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Extension: If Rebel’s main arm was treated as a flexible string, calculate the minimum velocity required at the top of the circle to keep tension on the string and continue rotation.

Assume no resistances, mass of the seats and riders equals 1800kg and the length of the main arm equalling 10 metres. Show working.

𝑇𝑒𝑛𝑠𝑖𝑜𝑛_{𝑇𝑜𝑝 𝑜𝑓 𝑐𝑖𝑟𝑐𝑙𝑒} = 𝑚𝑣

2 𝑇𝑜𝑝

𝑟 − 𝑚𝑔

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Q3 – Inertia and Torque

Extension: With refence to inertia and torque, briefly describe or discuss the following: - Why Rebel can reach its maximum height quicker when empty.

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- Why Rebel’s motors cannot rotate the main arm on the first go, and must build up speed.

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- The role of the counterweight and how it assists in the above questions.

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Tree Swing

Purpose

To investigate and discuss horizontal circulation motion. To compare period, frequency, time, speed

Draw a vertical free body diagram while at max speed. Show - Force due to gravity / weight force

- Tension force - Centripetal force

While observing the ride from outside the fence, use a stopwatch or similar to measure the time it takes the Tree Swing to complete five full rotations.

Seconds

From the above and using 𝑃𝑒𝑟𝑖𝑜𝑑 =_{𝐹𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦}1 → 𝑇 = 1

𝑓 and a maximum radius of 14.25m,

calculate:

- The period for a single full rotation

- The frequency of rotation

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Extension: Calculate the centripetal force required to move a full seat of mass 200kg from radius 5.25m to radius 14.25m 𝐹𝑜𝑟𝑐𝑒_{𝐶𝑒𝑛𝑡𝑟𝑖𝑝𝑒𝑡𝑎𝑙} = 𝑚𝑎𝑠𝑠 × 𝑠𝑝𝑒𝑒𝑑 2 𝑟𝑎𝑑𝑖𝑢𝑠_{𝑓𝑖𝑛𝑎𝑙}− 𝑟𝑎𝑑𝑖𝑢𝑠_{𝑖𝑛𝑖𝑡𝑖𝑎𝑙} ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________

Extension: Why is the velocity over one period 0. Calculate instead angular velocity, specify radians or degrees.

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Waterslides

Purpose

To experience the change in energy states, focussing on Boomerango. To discuss the effect of momentum while braking on single slides.

To experience the effect of horizontal circular motion through banking turns on the Redbelly Racer.

Extension: To experience and discuss superposition and harmonics in waves. Extension: To investigate the hydraulics required for our attractions.

The water park section of this workbook is intended to generate discussion and thought, rather than calculate the specific physics behind the concepts involved. Discussion is encouraged within the group and between the staff and parents / teachers.

Note-taking is encouraged to reflect and return to at later stages.

Suggested Water Park topics for discussion include:

• Potential energy change when climbing slide tower stairs, source of this energy

• Feeling of free-fall over Boomerango drop and moment of suspension at peak of Boomerango wave

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• Change in motion between heavy riders vs. lighter riders. How does the speed-brake work at the end of Racer and Body-slides work. How does weight / speed change the braking effect?

• Experience the banking turns through racer tubes, left vs right and discuss different between this and flat cornering.

• In wave pool, watch the diamond wave pattern and parallel patten and discuss differences between standing wave and travelling wave

• Extension: In wave pool, discuss how diamond waves are created using harmonics.