The change of speed is proportional to the Force. If you double the Force, you double the change of speed.
B) Energy from the sun is the answer, I am sure;
The water cycle is driven primarily by the energy from the sun<span>
. This </span>
solar energy<span>
drives the cycle by evaporating water from the oceans, lakes, rivers, and even the soil. Other water moves from plants to the atmosphere through the process of transpiration.</span>
Running means your body must convert stored glucose into energy through glycolysis.
m = 5 kg
a = 2 m/s²
to find the force that accelerates the 4 kg object @ 2 m/s²
F = ma = 5 kg x 2 m/s² = 10 N
To find what acceleration 10 N would give a 20 kg object
a = F/m = 10 N/20 kg = 0.5 m/s