general physics questions and answers

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Question:A beaker of water contains 300 mL of water. (1liter = 1000 cm^3). What is the volume of water in m^3? What is 28.84 m divided by 6.2 s with the correct number of significant figures?

Answers:Volume: 300 ml is 300 cm^3 300cm^3 is 3 x 10^-4 m^3 as [(3 x 10^2)/(100 x 100 x 100)] = 3 x 10^-4 Speed: 28.84/6.2 = 4.6516... =4.7m/s (only 2 s.f as only 2 in 6.2) When giving the correct number of significant figures, you should always give the answer to the same number as the least given. This is because after the significant figure, there could be any number which would still round to 6.2 in this case (eg 6.15, 6.18357, 6.249). This means that you cannot be any more accurate than the same number of significant figures, and adding more places in your answer will add error and mean that your answer is no longer likely to be correct, whereas it was before (if not very accurate)

Question:1. Explain how we hear sounds. 2. Describe how the meaning of sound is related to frequency and time. 3. Compare light and sound waves. 4. Describe the properties of light:describe light as both a wave and a particle. 5. Compare the speed of light with the speed of sound? 6. Explain the reason behind color blindness. Be sure to give accurated educational answers cause this is for my project. I do not have the time to read for all of the answer.

Answers:The answers you are looking for will take an enormous amount of time to answer. Each one would take thousands of volumes of books. I'm sorry I do not have the time to write the necessary answers.... e.g wave/particle duality is a vast subject!!

Question:Consider a particle moving in a straight line from initial point B to final point A, acted upon by a constant force F. (Part A figure) The force (think of it as a field, having a magnitude and direction at every position r ) is indicated by a series of identical vectors pointing to the left, parallel to the horizontal axis. The vectors are all identical only because the force is constant along the path. The magnitude of the force is F, and the displacement vector from point B to point A is L (of magnitude L, making and angle theta(radians) with the positive x axis). Find W(BA) , the work that the force F performs on the particle as it moves from point B to point A. Express the work in terms of L, F, and theta(angle). Remember to use radians, not degrees, for any angles that appear in your answer. the homework is online I put the answer: F*L and F*Lcos(theta) but computer says its wrong part a figur is a bent vector to the left from point B to A with theta between them and the x-axis (this is the best I can do to describe its simply just a vector)

Answers:Where is "Part A figure?"

Question:I can't seem to figure out a homework question...please help! The effect of air resistance is to slow down a moving object. It can be shown that the height of a falling object is given by the following: y = yo [t + (e^(-bt) 1)/b] g / b a) Show that for short times this reduces to the expected expression; y = yo 1/2gt2 b) Find the velocity & plot it as a function of time. What is the maximum velocity? c) Find the acceleration & plot it as a function of time. I have no idea how to even go about beginning to answer a. Also how would I figure out the points to plot velocity vs. time & acceleration vs. time?? Thanks in advance for your help!

Answers:a) If t is sufficiently small then bt will be small and you can express the exponential as a Maclaurin series; e^x = 1 + x + (1/2!)x^2 + ... for IxI < 1 In your case x = -bt and I believe you will need all three terms I have shown before you get a non-zero result. b) Differentiate your eq. to get V(t) V(t) = dY/dt = -(g/b) + (g/b)e^-(bt) c) Differentiate again to get ,a(t) a(t) = dV/dt = -(g)e^-bt When you graph these you are just looking for the general shape and key values. So look at extreme values of t, like t=0 and t = infinity and use your knowledge of exponential curves to fill in the rest.