Final answer:
If the mass of an object is doubled with no change in its net force, the new acceleration would be half of the original. Using Newton's second law, if an object with an acceleration of 18.0 m/s^2 has its mass doubled, the new acceleration is 9.0 m/s^2.
Step-by-step explanation:
If an object has an acceleration of 18.0 m/s2 and its mass is doubled (with no change in its net force), then its new acceleration would be 9.0 m/s2. This is determined using Newton's second law, which states that force equals mass times acceleration (F = ma). If the mass is doubled and the force remains the same, the acceleration must halve because the force is now distributed over twice the mass. To calculate the new acceleration (anew), we use the equation: anew = F / (2m), anew = (ma) / (2m) = a / 2, anew = 18.0 m/s2 / 2 = 9.0 m/s2.