Answer:
a. 125 kJ
Explanation:
Her total energy is the same as the potential energy she had at the top of the hill:
PE = mgh
= (52 kg)(9.8 m/s^2)(245 m) = 124,852 J
≈ 125 kJ . . . . matches choice A
_____
After skiing down 112 m, some of her initial energy is converted to kinetic energy, and some remains as potential energy. We assume the ski slope is essentially frictionless, and air resistance is negligible.
Answer: Larmor suggested in 1919 that a self-exciting dynamo could explain the magnetic field of the earth, as well as that of the sun and other stars, but it was Elsasser and Bullard in the 1940s who showed how motion in the liquid core of the earth might produce a self-sustaining magnetic field. By this time seismology and other studies had given a clearer picture of the earth, as having a solid inner core, a liquid outer core, both with a composition more of metal (mainly iron) than rock, and a rocky mantle, all below a thin crust that is all we can directly see. Energy from radioactivity travels outwards as heat, producing thermal convection in the core. It seems that this convection is the cause of the earth's magnetic field, although our knowledge of the core and its dynamics is sketchy. Our knowledge is limited to saying that flow regimes like those that may be occurring in the core can produce self-sustaining dynamos, with characteristics similar to that needed to produce the earth’s magnetic field.
Explanation:
Answer:
Option D is the correct answer.
Explanation:
We equation for elongation
Here we need to find weight required,
We need to stretch a steel road by 2 mm, that is ΔL = 2mm = 0.002 m
E = 200GPa = 2 x 10¹¹ N/m²
L=2m
Substituting
Option D is the correct answer.
Answer:
c. Kinetic energy is conserved in all collisions .
Explanation:
the total kinetic energy of system of particles involved in the collision does changes .
kinetic energy is not conserved in all collisions because in some cases energy is converted to another form of energy that is heat etc .
Answer:
person that you know and like (not a member of your family), and who likes you
