Carbon-13 has an atomic mass of 13.
Atomic mass is the sum of protons and neutrons.
There are 6 protons, so there are 13 - 6 = 7 neutrons.
Answer is 7 neutrons (and 6 electrons)
By using the formula density(p)= mass(kg)/volume(m^3) and gravitational acceleration (g)
Mass=2.5N/9.8m/s^2=0.26kg
Volume=0.1x 0.03^2 x3.142=0.009m^3
Density=28.89kg/m^-3
That's electric "current", usually described in 'Amperes'.
1 Ampere = 1 Coulomb per second ... "the rate at which
charge passes a point in the circuit".
If the object is moving in a straight line with constant speed,
that's a description of " acceleration = zero ".
Zero acceleration means zero net force on the object.
NO net force is 'required' to keep an object moving in a straight line
at constant speed. In fact, if there IS any net force on the object,
then either its speed or its direction MUST change ... there's no way
to avoid it.
None of this depends on the object's mass, or on the speed or direction
of its motion.