As a city planner, you receive complaints from local residents about the safety of nearby roads and streets. One complaint concerns a stop sign at the corner of Pine Street and 1st Street. Residents complain that the speed limit in the area (55 mph) is too high to allow vehicles to stop in time. Under normal conditions this is not a problem, but when fog rolls in visibility can reduce to only 155 ft. Since fog is a common occurrence in this region, you decide to investigate. The state highway department states that the effective coefficient of friction between a rolling wheel and asphalt ranges between 0.842 and 0.941, whereas the effective coefficient of friction between a skidding (locked) wheel and asphalt ranges between 0.550 and 0.754. Vehicles of all types travel on the road, from small VW bugs weighing 1070 lb to large trucks weighing 8070 lb. Considering that some drivers will brake properly when slowing down and others will skid to stop, calculate the minimum and maximum braking distance needed to ensure that all vehicles traveling at the posted speed limit can stop before reaching the intersection
. minimum braking distance: ft ? maximum braking distance: ft?
Given that the goal is to allow all vehicles to come safely to a stop before reaching the intersection, calculate the maximum desired speed limit. maximum speed limit: mph?
In: Physics
A box of mass m = 10.0 kg is attached to a rope. The other end of the rope is wrapped around a pulley with a radius of 15.0 cm. When you release the box, it begins to fall and the rope around the pulley begins to unwind, causing the pulley to rotate. As the box falls, the rope does not slip as it unwinds from the pulley. If the box is traveling at a speed of 2.50 m/s after it has fallen 0.500 m, what is the moment of inertia of the pulley?
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Two charges — q1 = 2.1 × 10-6C, q2 = 5.4 × 10-6C — are separated by a distance of d = 3.75 m.
At what distance, r in meters, from the first charge is the electric field zero?
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Starting from the basic definition of moment of inertia (eq 9.15), evaluate by integration the rotational inertia of a 50-lb hollow cylinder flywheel about the cylinder axis, whose outer diameter is 16-in and inner diameter is 15-in?
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Find the momentum space wavefunction of A/(x^2+a^2).
I need detailed, step-by-step explanation.
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1. As a demonstration of lab safety violations, a stainless steel water bottle is filled with a small amount of liquid nitrogen, and then the cap is sealed on the bottle (don’t ever do this – you could get seriously hurt). The bottle is laid on its side on the edge of the roof of the library building, which is 14 meters above the street below. When the bottle explodes, the 240 gram bottle flies back onto the roof and you measure its initial velocity to be 6.1 m/s. You can clearly see this velocity is initially completely horizontal. The 20.0 gram cap flies off the roof also with an initial velocity that is completely horizontal. How far away from the edge of the building does the cap land? You can assume air resistance is negligible.
2. You get a summer job testing springs at a manufacturing plant. Every 50th spring is taken off the line and is pushed with a force sensor a certain distance to make sure the spring constant is within specifications. The force sensor quits working. You devise a method using a flat track to push a 500 gram calibration mass along the track and then up a ramp angled at 20°. You cover the ramp and track with lubrication to make it nearly frictionless, but run out before you can coat the entire thing, leaving a 25 cm length on the flat part of the track with friction. Using a spring with a known spring constant of 150 N/m, you compress the spring 10 cm with the mass. You release the mass and measure it to go 23.0 cm along the angled part of the ramp when it stops. (a) What is the coefficient of friction of the patch left unlubricated? (b) If the springs you are currently manufacturing are supposed to be 400 N/m constants and you compress it 5 cm with the calibration mass, how far along the angled ramp should the calibration mass slide, assuming the friction is still present?
3. You set up a small ramp in your house to do some physics experiments. It is a smooth metal sheet and you are using an ice cube as a way to slide without friction. Your sheet is 1.42 meters long and you prop it up at an angle of 27°. You make a large ice cube of 250 grams for your experiment. a. If you allow the ice cube to slide from the top of the ramp, how fast is it going at the bottom? b. If the ice cube falls off the top of the ramp over the edge (instead of sliding down the ramp), how fast is it going when it hits the ground? c. If you wanted to slide the cube from the bottom of the ramp to the top, how much work would you do pushing it, assuming the speed at the bottom of the ramp and top of the ramp is zero? d. How much work does gravity do during the push from part (c)?
In: Physics
In: Physics
A space station shaped like a giant wheel has a radius of 1.00 x 102 m and a moment of inertia of 5.00 x 108 kgm2. A crew of 150 lives on the rim, and the station is rotating so that the crew experiences an apparent acceleration of 1.0g. When 120 people move to the center of the station for a union meeting, the angular speed changes. What apparent acceleration is experienced by the mangers remaining at the rim? Assume the average mass of a crew member is 65.0 kg.
Please show ALL work
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A ball of mass 0.576 kg moving east (+x+x direction) with a speed of 3.78 m/sm/s collides head-on with a 0.288 kg ball at rest. Assume that the collision is perfectly elastic
What is be the speed of the 0.576-kg ball after the collision?
What is be the direction of the velocity of the 0.576-kg ball after the collision?
What is the speed of the 0.288-kg ball after the collision?
What is the direction of the velocity of 0.288-kg ball after the collision?
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30 grams of ice at -5 Celsius melt while being left at room temperature of 28 Celsius. After melting its temperature rises to 28 Celsius. Determine the total change of entropy of the environment.
[Cice = .5 cal/g.C, Lf = 79.6 cal/gram] 1 calorie = 4.184 J
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Let the light ways moving from a material to another material. There are 2 scenarios:
- The ray is moving from water to glass. The intensity of the refracted rays is 98.92 % and the intensity of the reflected rays is 1.08%.
- The ray is moving from air to glass. The intensity of the refracted rays is 90.87% and the intensity of the reflected rays is 9.13%.
The index of diffraction of air, water, and glass are 1.00, 1.33, and 1.50 respectively.
Explain these differences in the intensity between 2 scenarios.
In: Physics
In: Physics
A boater dumps 2.00 kg of ice from a cooler into the lake at the end of a fishing trip. The ice is at a temperature of -8.00 oC and the lake water is at 15.0 oC. What is the change in entropy of the lake-ice cube system after the ice comes into equilibrium with the lake? Hint: the lake is very large.
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In: Physics
The naturally occurring isotope K40 is widely spread in the environment. In fact, the average concentration of potassium in the crustal rocks is 27 g/kg and in the oceans is 380 mg/liter. K40 occurs in plants and animals, has a half-life of 1.3 billion years and a natural abundance of 0.0119 percent.
Potassium's concentration in humans is 1.7 g/kg. In urine, potassium's concentration is 1.5 g/liter.
(You can skip i. I just need to know how to do ii, iii, iv. please) Thank you!
i) Calculate the specific activity of K40 in Becquerels per gram of K40.
ii) Calculate the specific activity of K40 in Becquerels per gram of K.
iii) Calculate the specific activity of K40 in urine in Bq/Liter
iv.) A beta activity above 200 transformations (disintegrations) per minute per liter of urine following exposure to fission products is indicative of an internal deposition. How does this "body burden" criterion compare to the activity caused by the one due to the naturally occurring potassium?
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