Final answer:
The acceleration of the helium balloon is approximately 0.392 m/s^2.
Step-by-step explanation:
The acceleration of a helium balloon can be calculated using the concept of buoyant force. The buoyant force is equal to the weight of the displaced air and is given by the formula Fb = ρair * V * g, where ρair is the density of air, V is the volume of the balloon, and g is the acceleration due to gravity. The weight of the balloon is given by the formula W = m * g, where m is the mass of the balloon.
Since there is no air resistance, the net force acting on the balloon is equal to the buoyant force minus the weight of the balloon, and the acceleration is given by the formula a = (Fb - W) / m.
Given that the volume of the balloon is 0.020 m3, the mass of the balloon is 25 g (or 0.025 kg), and the density of air is 1.3 kg/m3, we can calculate the buoyant force using the formula Fb = ρair * V * g = 1.3 kg/m3 * 0.020 m3 * 9.8 m/s2 = 0.2548 N. The weight of the balloon is equal to the mass of the balloon times the acceleration due to gravity, which is given by the formula W = m * g = 0.025 kg * 9.8 m/s2 = 0.245 N.
Therefore, the net force acting on the balloon is Fb - W = 0.2548 N - 0.245 N = 0.0098 N, and the acceleration a = (Fb - W) / m = 0.0098 N / 0.025 kg ≈ 0.392 m/s2.