4) Mass 1 is initially moving at 3 m/s in the +x direction and it collides perfectly elastically with mass 2 moving at 10 m/s in the -x direction. After the collision, mass 1 is moving at 5 m/s in the +x direction. What is the final velocity of mass 2 in m/s? If in the negative x direction, include a negative sign. (Note: the masses are not needed to answer this question.)
In: Physics
A beam of light in air is incident at an angle of 24.0° to the surface of a rectangular block of clear plastic ( n = 1.46). The light beam first passes through the block and re-emerges from the opposite side into air at what angle to the normal to that surface?
In: Physics
Because movie producers have come under pressure for teaching children incorrect science, you have been appointed to help a committee of concerned parents review a script for a new Superman movie. In the scene under consideration, Superman rushes to save Lois Lane who has been pushed from a window 300 feet above a crowded street. Superman is 0.5 miles away when he hears Lois scream and rushes to save her. He swoops down in the nick of time, arriving when Lois is just 3.0 feet above the street, and stopping her just at ground level. Lois changes her expression from one of horror at her impending doom to a smile of gratitude as she gently floats to the ground in Superman's arms. The committee wants to know if there is really enough time to express this range of emotions, even if there is a possible academy award on the line. The chairman asks you to calculate the time it takes for Superman to stop Lois's fall. To do the calculation, you assume that Superman applies a constant force to Lois in breaking her fall and that she weighs 120 lbs. While thinking about this scene you also wonder if Lois could survive the force that Superman applies to her.
In: Physics
Explain what the greenhouse effect is and discuss the cause and consequences of this to the planet. What evidence is there to show that “global warming ”has been the worst in the last ten years? Experts suggest that we must practice the three R’s to reduce the impact of global warming. Explain?
In: Physics
Calculate the final speed of an object dropped on Earth from altitude of 8 times the radius of Earth. (hint: neglect friction
due to atmosphere and use expression of gravitational potential energy and principle of conservation energy. Answer =
10.6 km/s).
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A trough is 11m long, 5m wide, and 3m deep. The vertical
cross-section of the trough parallel to an end is shaped like an
isoceles triangle (with height 3m, and base, on top, of length 5m).
The trough is full of water (density
1000kg/m3 and
g=9.8m/s2 is the acceleration due to
gravity).
a) Find the amount of work in joules required to empty the trough
by pumping the water over the top.
b) Find the amount of work in joules required to empty the trough
by pumping the water out of a spout 2m high.
In: Physics
5. For all setups, use a focal length of 2cm and place a real object to the left of the lens. For each case a-f:
i. Draw the ray diagram using principal rays.
ii. Determine whether the image is real or virtual, and where your eye would need to be to see the image.
iii. Estimate the image magnification from your drawing.
iv. Use the thin lens equation to check that the image location corresponds to your drawing.
v. Calculate the magnification and check it against your
estimate.
a. converging lens with object 6cm from lens (i.e. farther from the
lens than the focal point) b. converging lens with object 1cm from
lens (i.e. closer to the lens than the focal point) c. converging
lens with object at the focal point d. diverging lens with object
6cm from lens (i.e. farther from the lens than the focal point) e.
diverging lens with object 1cm from lens (i.e. closer to the lens
than the focal point) f. diverging lens with the object at the
focal point
In: Physics
Light can be seen through glass, water, and other transparent materials. When light is incident on a transparent material (such as water) at an angle, which of the following are true? (Select all that apply.)
A. The light will all be reflected and will not enter the transparent material.
B. The speed of the light changes as it enters the transparent material.
C. The frequency of the light changes as it enters the transparent material.
D. The speed of light remains constant as it enters the transparent material.
E. The direction of light remains constant as it enters the transparent material.
F. The frequency of the light remains constant as it enters the transparent material.
G. The direction the light is moving changes as it enters the transparent material.
In: Physics
Comment with a brief explanation whether the following statements are true or false:
1. The wavelength of an electron moving with a velocity of 1.1*10^6 m/s is 6.6 nm.
2. In photoelectric effect, whether an electron will be ejected by light is determined not by the intensity of light but by the wavelength.
3. The temperature of a star can be determined using its radiation spectrum.
4. Resistance-temperature-detector is based on resistivity of a metal decreasing with temperature.
In: Physics
1)What is the force between two equal charges (1 Coulomb) that are separated by a distance of 1 km? 2)Suppose that the charge of one of the charges in problem #1 is reduced to half of its original value. How does the new force compare to the original force?
In: Physics
1. Describe the basics of an astronomical telescope using light-ray diagrams.
2. What is the formula fr the magnification of an astronomical telescope made of lenses with focal lengths F_0 and F_e? Provide a brief, concise explanation; a drawing would help.
3. Describe the basics of a mircoscope using light-ray diagrams.
4. What is the basic difference between a telescope and a mircoscope and their constructions?
In: Physics
A wheel, starting from rest, rotates with a constant angular acceleration of 1.40 rad/s2. During a certain 6.00 s interval, it turns through 36.6 rad. (a) How long had the wheel been turning before the start of the 6.00 s interval? (b) What was the angular velocity of the wheel at the start of the 6.00 s interval?
In: Physics
PART A
A lens with two convex surfaces, both with radii of curvature of 0.25 meters, is used to focus light. If the lens is made of crown glass, it would have an index of refraction for red (656 nm) light of 1.509 and for blue light (486 nm) of 1.517. What happens when it is used to make an image of a distant source of white light? Pick those that apply (THERE ARE 3 ANSWERS)
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The red light falls in a cone outside the blue light as it the light converges to a focus, so when blue is in focus there is a fuzzy red ring around it. |
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The blue light focuses closer to the lens than the red light. |
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When the red light is in focus it is surrounded by a blue halo. |
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The red light focuses closer to the lens than the blue light. |
PART B
Energy carried by light..... Pick ALL that apply
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is proportional to both electric and magnetic fields |
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is proportional to the square of the electric field |
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is proportional to the amplitude of the electric field |
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flows perpendicular to both the electric and the magnetic fields |
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flows in the direction of the electric field |
PART C
Suppose you are experimenting with a Michelson interferometer and you have adjusted it so that you see a pattern of circular rings of interference. You illuminate the interferometer with light from sodium atoms which emit two wavelengths, 589 and 596 nm. What do you see? Pick ALL that apply. (there are multiple answers)
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For the same order of interference, the rings from the longer wavelength light fall inside the rings of the shorter wavelength light. |
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For some spacings of mirrors, the rings from the two lines may fall exactly between one another. |
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There are no rings visible because there are two wavelengths present. |
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You could adjust a mirror to make the rings of the two wavelengths lie on top of one another, and then change it to make them lie between one another. |
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The difference is so small that the rings from both wavelengths always lie on top of one another. |
In: Physics
A 0.30-kg puck, initially at rest on a frictionless horizontal surface, is struck by a 0.20-kg puck that is initially moving along the x-axis with a velocity of 8.6 m/s. After the collision, the 0.20-kg puck has a speed of 5.2 m/s at an angle of θ = 53° to the positive x-axis.
(a) Determine the velocity of the 0.30-kg puck after the collision.
(b) Find the fraction of kinetic energy lost in the collision.
In: Physics
The steel pipe (100 mm outer diameter) is covered with
two layers of insulation. The 40 mm thick inner layer has a thermal
conductivity of 0.07 W / (mK). Outer layer, 20 mm thick has a
thermal conductivity of 0.15 W / (m K). The pipe is used to drain
500 kPa pressurized steam. The temperature on the outer insulation
surface is 24 ° C. If the pipe is 8 m long, determine the
following: (assuming that the conduction heat transfer resistance
of steel pipes and vapor convection resistance is ignored).
a. Heat loss per hour. = kJ / hour.
b. Temperature between insulation layers. = ° C.
In: Physics