Two small spheres are suspended by strings of length L = 1.20 m from a ceiling at points d = 3.20 m apart. They have equal mass of m = 8.00 kg and equal and opposite charge of q = 1.40E-4 C. Calculate the angle or angles the strings make from vertical at equilibrium.
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A diver jumps vertically off a 10m platform, reaches a maximum height of 1.5m above the platform, and lands in a swimming pool below. Three seconds after entering the water, her downward motion is stopped. (a) What was her average acceleration in the water? (b) Sketch her position versus time, velocity versus time, and acceleration versus time. Check for consistency between the graphs and explain why your graphs are consistent.
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A block of mass 15kg rests on a wedge (θ=26∘). The two objects move to the right in such a way that the block doesn't slide up or down the wedge. The coefficient of static friction between the block and the wedge is 0.35. What is the minimum acceleration of the two objects? What is the maximum acceleration of the two objects?
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How much force is needed from the bicep which is 5 cm from the joint to overcome a 59 kg weight in the hand if the .7m long forearm has a mass of 5kg and the elbow is flexed to 90 degrees?
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A diver of mass m drops from a board 6.00 m above the water's surface, as shown in the figure. Neglect air resistance.
(a) Use conservation of mechanical energy to find his speed 3.00 m above the water's surface.
(b) Find his speed as he hits the water.
(c) Suppose the diver vaults off the springboard, leaving it with an initial speed of 3.68 m/s upward. Use energy conservation to find his speed when he strikes the water.
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A 486 nm laser beam shines on a diffraction grating. 5 bright fringes are measured to be 60 cm apart at a Scren Distance of 1.327m. What is the grating constant in cm^-1
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A demented scientist creates a new temperature scale, the "Z scale." He decides to call the boiling point of nitrogen 0 ∘Z and the melting point of iron 1000 ∘Z.
A) What is the boiling point of water on the Z scale?
B) Convert 100 ∘Z to the Celsius scale.
C) Convert 100 ∘Z to the Kelvin scale.
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1.) If your hands are wet and no towel is handy, you can remove excess water by shaking them. Use Newton's laws to explain why doing this gets rid of water.
2.) Newton's third law tells us that if you push a box with a 15 N force, it pushes back on you with a 15 N force. HOw can you ever acclerate this box if it always pushes back with the same force you exert on it.
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An organ pipe is 151cm\; cm long. The speed of sound in air is 343 m/s. Part A: What are the fundamental and first three audible overtones if the pipe is closed at one end? What are the fundamental and first three audible overtones if the pipe is open at both ends? Express awnsers to 3 signiicant figures seperated by commas
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A 54-kg box is being pushed a distance of 7.1 m across the floor by a force Upper POverscript right-arrow EndScripts ? whose magnitude is 188 N. The force Upper POverscript right-arrow EndScripts ? is parallel to the displacement of the box. The coefficient of kinetic friction is 0.23. Determine the work done on the box by each of the four forces that act on the box. Be sure to include the proper plus or minus sign for the work done by each force. (a) WP = (b) Wf = (c) Wmg = (d) WN =
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|
he food calorie, equal to 4186 J, is a measure of how much energy is released when food is metabolized by the body. A certain brand of fruit-and-cereal bar contains 130 food calories per bar. |
Part A If a 72.0 kg hiker eats one of these bars, how high a mountain must he climb to "work off" the calories, assuming that all the food energy goes only into increasing gravitational potential energy? Express your answer in meters.
SubmitRequest Answer Part B If, as is typical, only 25.0 % of the food calories go into mechanical energy, what would be the answer to Part A? (Note: In this and all other problems, we are assuming that 100% of the food calories that are eaten are absorbed and used by the body. This is actually not true. A person's "metabolic efficiency" is the percentage of calories eaten that are actually used; the rest are eliminated by the body. Metabolic efficiency varies considerably from person to person.) |
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A diver springs upward from a board that is 3.70 m above the water. At the instant she contacts the water her speed is 12.3 m/s and her body makes an angle of 78.5 ° with respect to the horizontal surface of the water. Determine her initial velocity, both (a) magnitude and (b) direction.
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Waves on a string are described by the following general equation
y(x,t)=Acos(kx−ωt).
A transverse wave on a string is traveling in the +xdirection with a wave speed of 8.50 m/s , an amplitude of 9.00×10−2 m , and a wavelength of 0.490 m . At time t=0, the x=0 end of the string has its maximum upward displacement. Find the transverse displacement y of a particle at x = 1.52 m and t = 0.150 s .
A) Find the transverse displacement y of a particle at x = 1.52 m at time t = 0.150 s .
B)How much time must elapse from the instant in part (c) until the particle at x = 1.52 m next has maximum upward displacement?
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Problem Scenario: A visit to the eye doctor! It is the time of the year when your family makes the annual visit to the eye doctor. In preparation you and your parents are writing down the specific issues you are facing with your eyes. None of you currently wear glasses. One of your parents says that they have been having trouble lately reading the newspaper. They can only see the newspaper clearly when it is at least dn = 50 cm from their eyes. But, they can comfortably see cars that are quite far away on the road. Your other parent says that they are also having trouble reading the newspaper and can read it if it is a similar distance dn = 50 cm away. However, they are also having trouble watching farther out: they can only clearly see stuff that is at most df = 2 m away. You say that you have not had trouble reading anything close to your eyes (about 25 cm away) but you are having trouble watching out for cars that are farther than df = 2 m away. You being the physicist in the family decide to follow the scientific method and figure out what type of lenses your optometrist would prescribe. You ask your parents whether they have a preference for glasses or contact lenses. You figure out the following preferences for your family: • You prefer contact lenses • Parent 1 (can not see close by, but can see far away) say that they prefer glasses that must must be placed d, = 2 cm from their eyes • Parent 2 can not see near or far) also wants glasses which must must be placed dy = 2 cm from their eyes With the above information you set out to find the power of each lens your eye doctor will probably) prescribe.
With the scenario: answer the following questions bellow
Your final report MUST include discussions of and answers to the following questions: 1). A clear ray diagram for each part of the scenario: you, parent 1, parent 2; eye only, eye + corrective lens, corrective lens only. Clearly mark the position of the object and the image. 2). Predict the power of each corrective lens required to fix the problem for you, parent 1, parent 2.
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