An object is thrown straight upward with an initial velocity of 1217 pixels per second. The vertical velocity of the object after 2 seconds is 0 due to gravity and the object is 1188 pixels above its starting point. The acceleration on the object due to gravity is 100 pixels per second squared. What is the mass of the object?
Just like with real gravity, the acceleration and motion of an object is independent of its mass whether measured in meters or pixels. So you cannot determine its mass other than to say that it is not zero. In order to determine mass you need force.