A 4.0-kg mass on the end of a string rotates in a circular motion on a horizontal frictionless table. The mass has a constant speed of 2.0 m/s and the radius of the circle is 0.80 m. What is the magnitude of the resultant force acting on the mass?
1) 39 N
2) 20 N
3) 44 N
4) 0 N
5) 30 N
Answer: 2