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April 2022 EXAMINATIONS

PHY205H1S

The Physics of Everyday Life

1.   [2 marks] Why must you bend forward when carrying a heavy load on your back? Explain using basic physics principles.

 

2.   [2 marks] You throw a ball straight upwards at 25 m/s. How high above its launch point will it reach? Which key assumption(s) did you need to make to solve this problem? Justify       whether they are reasonable or unreasonable assumptions in this situation.

 

3.   [2 marks] Some communities have sodium street lights that are mainly yellow with some   red. Which colours would be bad choices for painting police cars in these neighbourhoods? Which colours would be better choices? Explain.

 

4.   [2 marks] You and your two friends are designing a roller coaster. One friend says that    each summit must be lower than the previous one. The other says that as long as the first summit is the highest, it doesn’t matter what heights the others are. What do you say?      Explain your answer.


5.   [2 marks] A mouse is able to withstand falls from much greater heights without injury compared to a gorilla. Use a scaling argument to explain how this is possible.


6.   [2 marks] A styrofoam ball floats at the surface of a pond. A solid iron ball of the same size is dropped in the pond and now rests at the bottom. Which object has a greater buoyant     force acting on it? How do you know? Why does one float while the other sinks?


7.   [2 marks] The sitar, an Indian musical instrument, has a set of strings that vibrate and produce music, even though they are never plucked by the player. These sympathetic’ strings are identical to the plucked strings and are mounted below them. What is your   explanation?


8.   [2 marks] Are automobile headlamps wired in series or in parallel? Why? What evidence supports your conclusion?


9.   [2 marks] How does an electric transformer work? Why is AC required?


10. [2 marks] You can get a sunburn on a cloudy day but you can’t get a sunburn on a sunny day if you are behind glass. Explain.


11. [4 marks] You have a baseball and a light styrofoam ball that are the same size. If you drop them at the same time from a height of 2 m, which one will hit the ground first? Which one   will experience a greater force of air resistance during the fall? Explain.


12. [4 marks] You forget your 3 kg lunch bag on the top of your car before getting inside. The   car then accelerates North at 2 m/s2 for 5 seconds during which time the lunch bag does not slip. Relative to the ground, what is the acceleration of the lunch bag during this time?          Which important forces act on the bag and what are their magnitudes and directions? Use a force vector diagram to aid your explanation.


13. [4 marks] You slide down a snow-covered hill on a sled moving at a constant speed. Will carrying heavy weights with you in the sled allow you to slide down the hill at a greater    speed? Include a relevant force vector diagram in your explanation.


14. [4 marks] A flutist and a guitar player meet up on a cold day and tune their instruments (so that they hear a single steady tone when they play the same note). They come back the     next day which is warmer and play the same note. Now, they hear a beating pattern, even  though their instruments haven’t changed in any way. Explain. Refer to an equation as part of your explanation.


15. [4 marks] You have 2000 g of water at 80° C inside an electric kettle. The kettle’s element has a resistance of 20 Ω and it is connected to a 120 V outlet. In the ideal case where no  energy is lost to the surroundings, how long will it take to boil the water?