Year 12 VCE Physics at Luna Park

Name…………………………..

Year 12 VCE Physics at Luna Park

This booklet contains questions about 6 of the rides you are going on at Luna park. You must answer all of the general questions on page 2. You must also select 4 of these rides and answer all questions. This is valuable revision of many of the key concepts which you have already learnt about. You can also use this for revision of motion later on in the year.

This front page is for you to record measurements/observations which you will need to answer questions later:

Carousel: Time the period of the carousel:………………………………..

Twin Dragon: Time for one complete period (oscillation) of the twin dragon: ………………………………..

Number of passengers…………………

Silly Serpent: Time for one complete circuit……………………………

Number of curves: ………………..

Estimate of radius of each curve………………..

Estimate of mass of carriage…………………….

Estimate of height of track at highest………………..and lowest points:

Maximum number of passengers:……………………

You need to draw the shape of the track and put on labels to remind you where it is higher and lower.

Pharoah’s curse: Time for one full rotation:………………………….

Number of passengers…………………………..

Dodgem Cars: Time taken to travel approximately 5 metres………………………..

Estimate how much is the bumper bar compressed by when it hits a rail at maximum speed …………….

What is the floor like………………

What is the operator wearing on his feet?......

For each of the following situations, state a ride and when during that ride, that it occurs.

The vertical acceleration is zero, but you are moving ______
The vertical acceleration is greater than 9.8 m/s2 ______
The vertical acceleration is less than 9.8 m/s2 ______
Potential Energy is converted into Kinetic Energy ______
Kinetic Energy is converted into Potential Energy ______
Other forms of energy are being converted into Thermal Energy ______
The acceleration in the direction of motion is forward ______
The acceleration in the direction of motion is backward ______
The sideways acceleration is significant ______
Centripetal acceleration is directed horizontally ______
Centripetal acceleration is directed vertically upwards ______
centripetal acceleration is directed vertically downwards ______
A place where the effects of friction are immediately apparent ______
The ride that gives the greatest net force on you ______

Introduction:

When the thrill of the Scenic Railway has worn off and the fairy floss isn’t sitting well after the G-Force, then it’s time to head for the beauty of the Carousel! As you make your way around the ride perched on top of a horse built back in 1913, relax and consider the Physics involved in this historic ride.

The first, and most obvious movement associated with the Carousel is the circular motion.

You should be able to determine the frequency and period of your motion with a stop watch. Does it matter which horse you are riding on? How is your speed affected by your choice of horse?

Last but not least, where is the music coming from? Is it mounted on the moving or stationary part of the ride? Would it sound any different on the horse compared to someone standing outside watching?

Measurements

· Period using a stopwatch

Questions

1. As you travel around the carousel in a circular path at a constant speed, are you accelerating? Explain making reference to Newton’s laws.

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2. What is the direction of the acceleration? You may wish to use a vector diagram to confirm this answer.

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3. The radius of the path of the outer horses is 7.33m. Measure the period of the Carousel and calculate the speed of the outer horse.

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4. Now determine the centripetal acceleration of the outer horse.

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Imagine you were standing on the floor of the carousel with one of the fixed vertical rods on your inside (Note: It is not advisable to do this). You hold the rod for support. The net force on you is inwards because you are travelling in a circle.

5. Draw all the forces acting on you. Label each as Force by A on You, for example, your weight force is described as the Force by Earth on You.

6. What would you feel in your arm?

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7. If you now let go of the rod, what would you do to stay upright?

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8. If you now moved so that the rod is on your outside, draw all the forces acting on you.

9. What would you feel in your arm?

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History

The centre piece of the Park is the Carousel, housed in a purpose-built domed pavilion. It was built by the Philadelphia Toboggan Co. (PTC) of the USA in 1913 on order for the White City amusement park in Sydney. This park closed in 1918 and the Carousel was later purchased for £15,000 and moved to Luna Park, Melbourne.

The carousel was one of PTC’s “high class” rides, a grand machine designed for a permanent location. With a platform 52 feet in diameter, it still has the original 68 horses four abreast, 2 Roman chariots, elaborate decoration and 36 cherubs frozen in flight on the rounding boards. 26 original scenery paintings adorn the centre panels and rounding boards, painted by PTC’s Max Soltmann. During the restoration of PTC#30, it was discovered that much of the original paint was intact on the majority of horses, rounding boards and centre panels. Check http://www.lunapark.com.au.

Ride Information Provided By Luna Park

Radius, that is, the distance from the axle to seat level: 12m

Length of rubber strip on the bottom of the dragon boat: 10 m

Angle between the left and right boat supports: 32º

Mass of the dragon boat: 2200 kg

Max swing: 60º each way

Measurements Needed

· The time for a single oscillation (that is, the boat’s movement from one side, to the other, and back to where it started from) when the ride is operating at its maximum.

Draw a sketch-diagram of the Twin Dragon ride and label the above information appropriately on the ride.

2. As the ride starts from stationary, using point-form, briefly describe how the ride reaches its maximum speed. Use concepts such as “gravitational potential energy,” “kinetic energy,” “mechanical energy,” and “friction”.

3. How many people are on-board the ride?

4. The weight of an average adult person is estimated by engineers as between 65 kg and 70 kg. Using the 70kg estimate, what is the estimated total mass of the boat including the occupants?

5. While it is swinging from side-to-side, the twin dragon can be said to be undergoing wave-like motion. What name is given to the time it takes for the boat to complete one oscillation?

6. When it is operating at its maximum, time how long it takes the ride to complete a cycle. (Note: A more accurate reading would be obtained by measuring the time for 4 or 5 complete cycles and then dividing that time by the number of cycles.)

7. What is the frequency of the ride’s oscillation (that is, the number of oscillations or part of an oscillation per second? ......

During the course of the boats pendulum movement – that is swinging from side to side – the oscillations can be thought of as consisting of Vertical Movement and Horizontal Movement.

Horizontal Movement

8. At what point(s) during the boat’s motion is the horizontal velocity 0 ms-1 ?

9. At what point(s) during the pendulum motion is the horizontal velocity a maximum?

Vertical Movement

10. At what point(s) during the boat’s motion is the vertical velocity 0 ms-1 ?

11. At what point(s) during the boat’s motion is the vertical velocity a maximum?

Momentum

12. At what point in the boat’s swinging movement is horizontal momentum a maximum?

13. At what point in the boat’s swinging movement is horizontal momentum 0 kgms-1 ?

14. When is vertical momentum 0 kgms-1 ?

15. When is vertical momentum at a maximum?

The

Coney

Island

Top

Drop

Data: Mass of 10 person carriage = 1150 kg. Include units in your answers.

1. On the diagrams below, draw a vector (when needed) to represent the direction of the net force on a rider in the chair. Label this FNET.

a) Stationary at X at the top b) in free fall between X and Y c) braking between Y and Z

Free fall 3.5 m

a = 9.8 m/s2

Braking 0.8m

2. Now on each of the diagrams draw in a vector for the weight force (when needed), labelled W

3. Now on each of the diagrams draw in a vector for the reaction force by the chair on the rider (when needed), labelled R. Consider the size as well as the direction of this force.

4. Energy

(a) How much work is done by the cables to raise the chair and riders from Z to X?

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(b) What is the decrease in Gravitational Potential Energy of the carriage when full (assume your body mass) as it falls from position X to Y?

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(d) Use this to find out how fast the carriage and its occupants are falling at the end of free fall, Y?

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5. Kinematics and Dynamics

(a) Use your answer from 4(d) to calculate how long you are in free fall from stationary at X to the point Y, 3.5 m lower:

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(b) From Y to Z the seat decelerates under braking from the speed calculated in 2(d) to zero. Assume this deceleration is constant, calculate its size:

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(c) How many “gees” is this acceleration in 5b that the riders experience? (That is, how many times is this greater than the acceleration due to gravity, 9.8 m/s2).

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(d) What force does the cushioning have to supply to bring the carriage to rest over this distance?

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(e) You “feel” your weight through the reaction force acting on you, i.e. the force by chair on rider. This is called your apparent weight. Determine your apparent weight at

i) Position X ii) In free fall iii) During deceleration from Y to Z

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Silly Serpent

Drawings

1. Draw the shape of the track

a) Label the points on the track where you would experience;

b) The highest speed

c) The highest acceleration

d) The highest gravitational potential energy

e) The highest kinetic energy

2. Draw a diagram of you sitting in a carriage at the highest point on the track during the ride. Draw in all the forces acting on you at this point. Label the forces as “Force by A on You”.

3. On the drawing of the first two cars below draw in the forces acting on the Serpent car as the ride starts off. Label the forces as “Force by A on B”.

4. Using another coloured pen draw in the net force acting on a passenger in the carriage at this point.

Estimations

Your mass ______kg. The mass of the empty carriage ______kg

Height of rail at the lowest point _____ m. Maximum height of the rail ______m

Number of curves ____. The radius of each curve _____ m.

Distance traveled by the Serpent in one second _____ m.

The total circumference of each curve added to give the total distance around the track ______m.

Measure the time for one rotation of the serpent = ______seconds.

Stopping distance = ______m. Stopping time = ______s.

Calculations (include units)

1. Using your estimation for the total distance around the track calculate your average velocity as you complete one circuit.

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2. Using the average velocity and the radius for each curve, calculate the centripetal acceleration on you.

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3. Using the formula for gravitational potential energy, work out your change in potential energy as the serpent ride lifts you from the lowest point to the highest point.

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What is your total energy at this point in the ride?

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4. Count the maximum possible number of passengers and the number of carriages . Calculate the maximum total mass of passengers when the ride is full. Use this with the average velocity to calculate the maximum momentum of the Serpent ride.

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5. When the ride stops what happens to this momentum?

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6. Calculate the braking force required to stop the whole ride.

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7. Work out the total kinetic energy of the serpent ride before it stops.

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8. What happens to this energy when the Serpent stops?

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Equipment needed: stopwatch, calculator

The Pharoah’s Curse has two gondolas for passengers which swing in opposite directions. As the gondolas swing backwards and forwards, the angle increases each time until the gondolas go over the top. The length of the arms is 9.0 metres.

Full rotation

1. When the gondolas reach full rotation, measure the time for one rotation, calculate the average speed of rotation. (v=2pr/T)

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2. Assuming this speed is constant, what is the size of the centripetal acceleration?

(a = v2/r, a = 4p2r/T2)

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3. Draw, on the figure of you in the diagram, arrows to represent:

a) the centripetal acceleration, a

b) your weight force (labelled as W) and

c) the reaction force by the seat on you

(labelled as R).

Consider both the size and direction of these two forces.

Gondola at the bottom of its swing

4. Estimate the kinetic energy of each gondola as it rotates in a full rotation.? The mass of each gondola is 2100kg, estimate the total mass of the passengers.

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5. Looking at your answer to Q’n 4, can you suggest why the drive mechanism is hydraulic rather than mechanical? Consider the effect of gears and sudden changes in speed or power loss.