A hot-air balloon is accelerating upward under the influence of two forces, its weight and the buoyant force. For simplicity, consider the weight to be only that of the hot air within the balloon, thus neglecting the balloon fabric and the basket. The hot air inside the balloon has a density of ρhotair = 0.89 kg/m3, and the density of the cool air outside is ρcool air = 1.29 kg/m3. Calculate the acceleration of the rising balloon?