Hello there!
Your question can be answered using the Newton's Secon Law of Motion:
This Law says that the forces on an object are equal to the product of its mass (m) and acceleration (a):
[tex]F=m*a[/tex]
If we clear this equation for acceleration, we'll see that:
[tex]a= \frac{F}{m} [/tex]
So, studying this equation, we'll see that acceleration is inversely proportional to mass, thus, assuming that the force remains constant, doubling the mass will decrease the acceleration of the object by half.
