Unreasonable Results A car advertisement claims that its 900-kg car accelerated from rest to 30.0 m/s and drove 100 km, gaining 3.00 km in altitude, on 1.0 gal of gasoline. The average force of friction including air resistance was 700 N. Assume all values are known to three significant figures. (a) Calculate the car's efficiency. (b) What is unreasonable about the result? (c) Which premise is unreasonable, or which premises are inconsistent?
Unreasonable Results A car advertisement claims that its 900-kg car accelerated from rest to 30.0 m/s and drove 100 km, gaining 3.00 km in altitude, on 1.0 gal of gasoline. The average force of friction including air resistance was 700 N. Assume all values are known to three significant figures. (a) Calculate the car's efficiency. (b) What is unreasonable about the result? (c) Which premise is unreasonable, or which premises are inconsistent?
A car advertisement claims that its 900-kg car accelerated from rest to 30.0 m/s and drove 100 km, gaining 3.00 km in altitude, on 1.0 gal of gasoline. The average force of friction including air resistance was 700 N. Assume all values are known to three significant figures. (a) Calculate the car's efficiency. (b) What is unreasonable about the result? (c) Which premise is unreasonable, or which premises are inconsistent?
Definition Definition Force that opposes motion when the surface of one item rubs against the surface of another. The unit of force of friction is same as the unit of force.
Answers with -1.828, -1.31 or 939.3 are not correct.
Three slits, each separated from its neighbor by d = 0.06 mm, are illuminated by a coherent light source of
wavelength 550 nm. The slits are extremely narrow. A screen is located L = 2.5 m from the slits. The
intensity on the centerline is 0.05 W. Consider a location on the screen x = 1.72 cm from the centerline.
a) Draw the phasors, according to the phasor model for the addition of harmonic waves, appropriate for this
location.
b) From the phasor diagram, calculate the intensity of light at this location.
A Jamin interferometer is a device for measuring or for comparing the indices of refraction of gases. A beam
of monochromatic light is split into two parts, each of which is directed along the axis of a separate cylindrical
tube before being recombined into a single beam that is viewed through a telescope. Suppose we are given the
following,
•
Length of each tube is L = 0.4 m.
• λ= 598 nm.
Both tubes are initially evacuated, and constructive interference is observed in the center of the field of view. As
air is slowly let into one of the tubes, the central field of view changes dark and back to bright a total of 198
times.
(a) What is the index of refraction for air?
(b) If the fringes can be counted to ±0.25 fringe, where one fringe is equivalent to one complete cycle of
intensity variation at the center of the field of view, to what accuracy can the index of refraction of air be
determined by this experiment?
Physics for Scientists and Engineers: A Strategic Approach, Vol. 1 (Chs 1-21) (4th Edition)
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