A $100\mathrm{kg}$ rock is in space, far from any planets, stars or black holes. It is moving in a straight line at a constant $\mathrm{10,000}\mathrm{m}/\mathrm{s}$ relative to our sun. What total force is required to keep it moving that fast?

• A. $100\mathrm{kg}$
• B. $100\mathrm{N}$
• C. $\mathrm{9,800}\mathrm{N}$
• D. $\mathrm{1,000,000}\mathrm{N}$
• E. $0\mathrm{N}$

Answer: (E)

Verified step by step guidance

1. Identify the key concept: According to Newton's First Law of Motion, an object in motion will stay in motion at a constant velocity unless acted upon by a net external force.
2. Recognize that the rock is in space, far from any gravitational influences, meaning there are no external forces acting on it.
3. Understand that since the rock is moving at a constant velocity, there is no acceleration. According to Newton's Second Law, force is the product of mass and acceleration (F = ma).
4. Since the acceleration is zero (because the velocity is constant), the net force required to maintain this motion is also zero.
5. Conclude that the total force required to keep the rock moving at 10,000 m/s is 0 N, as no force is needed to maintain constant velocity in the absence of external forces.