An individual is nearsighted; his near point is 12.0 cm and his far point is 51.0 cm.
(a) What lens power is needed to correct his nearsightedness?
[answer] diopters
(b) When the lenses are in use, what is this person's near point?
[answer] cm
In: Physics
A: A bird watcher meanders through the woods, walking 0.30 km due east, 0.80 km due south, and 2.30 km in a direction 45.0° north of west. The time required for this trip is 4.00 h.
(a) Determine the magnitude and direction (relative to due west) of the bird watcher's displacement. Use kilometers and hours for distance and time, respectively.
(b) Determine the magnitude and direction (relative to due west) of
the bird watcher's average velocity.
B: An airplane is flying with a velocity of 226 m/s at an angle of 30.0° with the horizontal, as the drawing shows. When the altitude of the plane is 2.1 km, a flare is released from the plane. The flare hits the target on the ground. What is the angle θ?
C: After leaving the end of a ski ramp, a ski jumper lands downhill at a point that is displaced 33 m horizontally from the end of the ramp. His velocity, just before landing, is 18.5 m/s and points in a direction 43° below the horizontal. Neglecting air resistance and any lift he experiences while airborne, find his initial velocity (magnitude and direction), when the he left the end of the ramp.
| magnitude | m/s |
| direction |
° counterclockwise from the positive x axis |
In: Physics
1.45 kg of ice at -5 ∘C is dropped into 31 kg of water at temperature 15.3 ∘C .
Part A - Final Temperature
What is the final temperature of the system? (If I've set the problem up right, you should be given numbers such that all of the ice has melted.)
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| Tf = | ∘C |
Part B - Entropy of Warming Ice
What is the change in entropy of the ice, as it warms up before melting?
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| S = | J/K |
Part C - Entropy of Ice Melting
What is the change in entropy of the ice as it melts?
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| S = | J/K |
Part D - Entropy of Water From Ice Warming Up
After the ice melts, it's just water, and this water still has to warm up to the final temperature. What is the entropy change of this process?
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| S = | J/K |
Part E - Change in Entropy of the Water Cooling
Meanwhile, the initially warm water is cooling down. What is the entropy change of this water, which is undergoing cooling?
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| S = | J/K |
Part F
What is the total change in the entropy of the system?
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| S = | J/K |
In: Physics
A magnetic field is perpendicular to the plane of a single-turn circular coil. The magnitude of the field is changing, so that an emf of 0.81 V and a current of 3.8 A are induced in the coil. The wire is then re-formed into a single-turn square coil, which is used in the same magnetic field (again perpendicular to the plane of the coil and with a magnitude changing at the same rate). What (a) emf and (b) current are induced in the square coil?
In: Physics
A 89.35-kg skier with an initial speed of vi=43.91 m/s coasts up a H=15.58-m-high rise as shown in the figure. The slope angle is theta=50.33. What is her final speed at the top? Assume the coefficient of friction between her skis and the snow is 0.069 (Hint: Find the distance traveled up the incline assuming a straight-line path as shown in the figure.) Use g = 10 m/s2.
In: Physics
A small circular coil with a radius of 1.00 cm has 20 turns and carries a current. A magnetic field probe is located somewhere along the coil's central axis, much farther from the coil's center than the coil's radius.
A. The probe indicates that the magnetic field points down the axis, towards the center of the coil. Looking down the axis towards the coil, the current must be flowing which way? (clockwise or counterclockwise)
B. At a distance of 3.0 meters from the center of the coil, the probe indicates that the coil's magnetic field has a magnitude of 13.0 pT (10-12 T). How much current is flowing in the coil?
C.How strong is the field at the center of the coil, in Gauss?
D. If the probe is moved to a distance of 9.0 meters from the center of the probe, how much weaker the magnetic field it detects be?
In: Physics
In laboratory tests, a new construction material was found to conduct heat at a rate of 10.2 Btu’s per hour per square meter of surface area. The temperature on one side of the wall was held at a constant 5 F while the other side was held at 70 F. The test specimen was 12.0 inches thick. What is the ambient air temperature (F) on the warm side of the wall? Assume there is free convection on the warm side of the wall, and the warm side is indoors.
In: Physics
On the Apollo 14 mission to the moon, astronaut Alan Shepard hit a golf ball with a golf club improvised from a tool. The free-fall acceleration on the moon is 1/6 of its value on earth. Suppose he hit the ball with a speed of 33 m/s at an angle 36 ∘∘ above the horizontal.
A. How long was the ball in flight? Express your answer with the appropriate units.
B. How far did it travel? Express your answer with the appropriate units.
C. Ignoring air resistance, how much farther would it travel on the moon than on earth? Express your answer in meters.
In: Physics
Please select True or False: For a satellite in a non-circular, closed, fixed orbit around the Earth, answer which of the following are always true or always false for Kinetic Energy (KE) and Potential Energy (PE).
Answer the following with ;
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False |
| B. |
True for Einsteinian (relativistic) Physics but not true for Newtonian (traditional or non-relativistic) Physics |
| C. |
True |
| D. |
Undefined and/or Not Applicable |
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1. The satellite's KE and PE are both at their minimum value over the entire orbit when the satellite is at apogee |
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2. The satellite's KE and PE are both at their maximum value over the entire orbit when the satellite is at apogee |
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3. The satellite's KE is at its maximum value over the entire orbit and its PE is at its minimum value over the entire orbit when the satellite is at perigee |
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4. The satellite's KE is at its maximum value over the entire orbit and its PE is at its minimum value over the entire orbit when the satellite is at apogee |
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5. The satellite's KE and its PE are equal when the satellite is at apogee |
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6. The satellite's KE is at its minimum value over the entire orbit when the satellite is at apogee |
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7. The satellite's PE is at its maximum value over the entire orbit when the satellite is at perigee |
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8. The satellite's PE is at its maximum value over the entire orbit and its KE is at its minimum value over the entire orbit when the satellite is at apogee |
In: Physics
The magnetic field inside a 4.0-cm-diameter superconducting solenoid varies sinusoidally between 8.0 T and 12.0 T at a frequency of 7.0Hz .What is the maximum electric field strength at a point 2.0cm from the solenoid axis? What is the value of B at the instant E reaches its maximum value?
In: Physics
A beam of length L and mass M rests on two pivots. The first pivot is at the left end, taken as the origin, and the second pivot is at a distance , from the left end. A woman of mass m starts at the left end and walks toward the right end. When the beam is on the verge of tipping, find symbolic expressions for (a) the normal force exerted by the second pivot in terms of M, m, and g and (b) the woman
In: Physics
Determine the expression of the electric field and the electric potential from 0 to infinity along a hollow conductive disk and assuming that a point charge Q is placed in its center. R1 and R2 are the inner and outer radius of the disk respectively.
In: Physics
Apply the continuity equation in the following scenario to determine the fluid velocity at the outlet of the pipe shown in the drawing below. State all reasonable assumptions and show ALL of your work, Ensure that you provide the appropriate units for your answer.
Working fluid: water at STP
Inlet mass flow rate: 500lbm/hr
inlet pipe diameter: 24 inches outlet pipe diameter: 9 inches
inlet fluid velocity: 200 feet/sec Outler fluid velocity:????
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What is electrical potential? How is it related to electric potential energy? How is it related to electric field? How can you calculate the electrical potential?
In: Physics
A 3.36 µC charge is 1.17 cm from a 5.67 µC charge. How far from the larger charge will the electric field be zero? Answer in cm.
In: Physics