Answer:
The answer <em><u>is C. Mars</u></em>. Mars and Mercury are both smaller than Earth's core. Hope this helps you :)
A simple electromagnet consisting of a coil of insulated wire wrapped around an iron core<span>. A </span>core<span> of ferromagnetic material like </span>iron<span> serves to increase the magnetic field created. The strength of magnetic field </span>generated<span> is proportional to the amount of </span>current<span> through the winding.</span>
Jane's mechanical energy at any time is

where

is the potential energy, while

is the kinetic energy.
Initially, Jane is on the ground, so the altitude is h=0 and the potential energy is zero: U=0. She's running with speed v, so she has kinetic energy only:

Then she grabs the vine, and when she reaches the maximum height h, her speed is zero: v=0, and so the kinetic energy becomes zero: K=0. So now her mechanical energy is just potential energy:

But E must be conserved, so the initial kinetic energy must be equal to the final potential energy:

from which we can find h, the maximum height Jane can reach:
<span>A 67.0 kg crate is being raised by means of a rope. Its upward acceleration is 3.50 m/s2. What is the force exerted by the rope on the crate?
</span>Newton's Second Law<span> of Motion states, “The force acting on an object is equal to the mass of that object times its acceleration.” We calculate as follows:
</span>
F = ma = 67.0 kg (3.50 m/s^2) = 234.5 J