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Questions in physics

[Done] Explain how the atoms of the element helium are formed in a star.

[Done] The coordinates of a bird flying in the xy-plane are given by [tex]x(t) = \alpha t[/tex] and [tex]y(t) = 3.0 \, \text{m} - \beta t^2[/tex], where [tex]\alpha = 2.4 \, \text{m/s}[/tex] and [tex]\beta = 1.2 \, \text{m/s}^2[/tex]. Part a: Calculate the velocity vector of the bird as a function of time. Give your answer as a pair of components separated by a comma. For example, if you think the x component is 3 and the y component is 4, then you should enter 3,4. Part b: Calculate the acceleration vector of the bird as a function of time. Give your answer as a pair of components separated by a comma. For example, if you think the x component is 3 and the y component is 4, then you should enter 3,4.

[Done] What are the various ways in which lithospheric plates interact with each other as they move around on a dynamic Earth?

[Done] What happens to the magnetic domains in a material when the material is placed in a strong magnetic field?

[Done] Explain how light travels.

[Done] What is friction? Explain.

[Done] A cheetah runs with a positive acceleration. What does this tell you about the velocity-time graph for the cheetah? A. Graph with a negative slope B. Graph with a positive slope C. Graph with a positive area D. Graph with a negative area

[Done] There are 10 apples in a one-kilogram bag of apples. What is the average mass of each apple in the bag? Give your answer in units of kilograms and grams.

[Done] A horse starts from rest and speeds up with constant acceleration. If it has gone a distance of 100 m at the point when it reaches a speed of 12 m/s, what is its acceleration?

[Done] An ambulance driving with velocity \(\frac{v}{8}\), where \(v\) is the speed of sound, emits a siren with a frequency of [tex] f_0 [/tex]. What is the frequency heard by a stationary observer toward whom the ambulance is driving?