Answer:

Explanation:
From the question we are told that
Velocity v=28m/s
Distance d=280
Generally the Newtons equation for motion is mathematically given as
Acceleration




i do not know.....................................
Answer:
The ratio of the Broglie wavelength of an electron to that of the proton is 42.85.
Explanation:
let λe be the Broglie wavelength of the electron and λp be the Broglie wavelength of the proton, Me be the mass of the electron and Mp be the mass of the proton. let h be the Planck constant, Kep be the kinetic energy of the proton and KEe be the kinetic energy of the electron
Answer:
<em>Sara must climb 10609 stairs to burn this food.</em>
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Explanation:
Chemical energy content in Sara's body = 788 kCal x 4.184 = 3296.99 kJ = 3296990 J
her body is only 25% effective in converting chemical to mechanical energy, therefore,
available mechanical energy = 25% of 3296990 = 0.25 x 3296990 = <em>824247.5 J --this is equivalent to the work she must do to burn this stored energy</em>
flight of stairs = 12 cm = 0.12 m
Sara's mass m = 66 kg
Sara's weight = mg = mass x acceleration due to gravity 9.81 m/s^2
weight W = 66 x 9.81 = 647.46 N
work done = force x distance climbed d
putting in the necessary values, we have
824247.5 = 647.46 x d
d = 1273.05 m
the number of stairs Sara must climb is equal to the distance climbed divided by the height of a single stairs
number of stairs = 1273.05/0.12 = 10608.75 ≅ <em>10609 stairs</em>