To calculate the force needed to move a 0.1 kg snowball at a rate of 15 m/s upward, we can use Newton's second law of motion, which states that the force acting on an object is equal to the mass of the object multiplied by its acceleration.

The formula for this is:

Force = Mass × Acceleration

In this case, the mass of the snowball is 0.1 kg, and the acceleration is 15 m/s upward. So, the force needed to move the snowball is:

Force = 0.1 kg × 15 m/s²

Force = 1.5 Newtons

Therefore, a force of 1.5 Newtons is needed to move a 0.1 kg snowball at a rate of 15 m/s upward.