Science Homework Help

7. (I) Write an equation that describes a transverse wave that is moving to the

-x direction, that has a speed of 20.0 m/s. The y position an element of the

wave is zero at time t = 0 and position x = 0.0m. The maximum transverse

speed and the magnitude of the maximum transverse acceleration of an

element in the medium are 3.0 m/s and 240.0 m/s2. (II) What is the

frequency and wavelength of the waves? (III) What is the velocity of the

element at x = 0.5m and t = 0.2s?

9. You stand in the middle of a basketball court, holding a tuning fork of

frequency f. You now run towards the wall at one side of the court with a

speed vp. (I) What is frequency of beats due to the interference of sound

from the tuning fork itself and those reaching you after reflected from the

wall in front of you? (II) What is the frequency of beats due to the sound

reflected from the wall in front of you and the reflected sound from the

wall behind you? For part (I) & (II), show your answer in terms of speed of

sound v, f, and vw. (III) find the beat frequency in part I & II if you are

running at 5m/s, and the speed of sound is 335 m/s. The tunning fork

frequency is 400Hz. (IV) Based on your results in (III), can you detect both

the beats in part (I) & (II)?

10. You are holding a cosmetic mirror (Not a plane mirror!) in front of your

face. The focal length of the mirror is 15.0cm. Model your eye as a single

converging lens with adjustable focal length. The retina is 2.20cm behind

the lens. (I) What is the focal length of your eye lens such that a clear image

of your eye can be formed on the retina when you are holding the mirror

10.0cm from your face ? (II) Is the image formed on the retina upright, or

inverted? (III) If the vertical dimension of your eye is about 3.0cm, what is

the size of the image of you eye formed on the retina?