A mass of 5 kg slides across a frictionless table with an initial velocity of 10 m/s. The wind
 starts to blow in the direction the mass is moving causing it to accelerate at a constant rate.
 After 2 seconds, the mass is moving at a velocity of 15 m/s. What is the acceleration of the
 mass?
 A 12.5 m/s 2
 B 7.5 m/s 2
 C 5.0 m/s 2
 D 2.5 m/s