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PHYSICS, M2 2021 VCE 9a

Abbie and Brian are about to go on their first loop-the-loop roller-coaster ride. As competent Physics students, they are working out if they will have enough speed at the top of the loop to remain in contact with the track while they are upside down at point \(\text{C}\), shown in Figure 9. 
 

The highest point of the roller-coaster (point \(\text{A}\)) is 15 m above point \(\text{B}\) and the car starts at rest from point \(\text{A}\). Assume that there is negligible friction between the car and the track.

What is the speed of the car at point \(\text{B}\) at the bottom of the loop? Show your working.  (2 marks)

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\(17.1\ \text{ms}^{-1}\)

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Using the Law of Conservation of Energy: 

\(mgh\) \(=\dfrac{1}{2}mv^2\)  
\(v\) \(=\sqrt{2gh}\)  
  \(=\sqrt{2 \times 9.8 \times 15}\)  
  \(=17.1\ \text{ms}^{-1}\)  

PHYSICS, M2 2018 HSC 23a

The diagram shows a cathode ray tube in a television.
 

Outline energy changes associated with the electrons passing through the gun, and when they strike the screen.   (2 marks)

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→ As the electrons pass through the gun, they experience an acceleration and so have their kinetic energy increased and the electrical potential energy decreased.

→ When the electrons hit the screen, their kinetic energy is converted into light and heat energy by the law of conservation of energy.

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→ As the electrons pass through the gun, they experience an acceleration and so have their kinetic energy increased and the electrical potential energy decreased.

→ When the electrons hit the screen, their kinetic energy is converted into light and heat energy by the law of conservation of energy.

Mean mark 54%.