meg runs a 10-km race in 45 minutes (0.75 hours). what was her speed in kilometers per hour ? a. 7.5 km/hr b. 4.5 km/hr c. 13 km
1 answer:
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Answer:
1keff=1k1+1k2
see further explanation
Explanation:for clarification
Show that the effective force constant of a series combination is given by 1keff=1k1+1k2. (Hint: For a given force, the total distance stretched by the equivalent single spring is the sum of the distances stretched by the springs in combination. Also, each spring must exert the same force. Do you see why?
From Hooke's law , we know that the force exerted on an elastic object is directly proportional to the extension provided that the elastic limit is not exceeded.
Now the spring is in series combination
Fe
F=ke
k=f/e.........*
where k is the force constant or the constant of proportionality
k=f/e
............................1
also for effective force constant
divide all through by extension
1) Total force is
Ft=F1+F2
Ft=k1e1+k2e2
F = k(e1+e2) 2)
Since force on the 2 springs is the same, so
k1e1=k2e2
e1=F/k1 and e2=F/k2,
and e1+e2=F/keq
Substituting e1 and e2, you get
1/keq=1/k1+1/k2
Hint: For a given force, the total distance stretched by the equivalent single spring is the sum of the distances stretched by the springs in combination.
Answer:
(a) False
(b) True
(c) True
(d) True
(e) True
(f) True
Explanation:
(a) Maxwell's equations not only applies to constant fields but it applies to both the fields, i.e., Time variant field as well as Time Invariant field.
(b) We make use of the Modified form of the Ampere's law and Faraday's Law to derive the wave equation.
(c) Electromagnetic waves contains both the electric and magnetic fields and these fields oscillates at an angle of to the direction of wave propagation.
(d) In free space both the electric and magnetic fields are in phase while considering electromagnetic waves.
(e) In free space or vacuum, the expression for the speed of light in terms of electric and magnetic field is given as:
Thus the ratio of the magnitudes of the electric and magnetic field vectors are equal to the speed of light in free space.
(f) In free space or in vacuum the energy density of the electromagnetic wave is divided equally in both the fields and hence are equal.