Does a black cup keep water hotter than a white cup?

Yes, a black cup can keep water hotter than a white cup due to its color. Black surfaces absorb more heat and can retain warmth better than lighter colors, which reflect more light and heat. However, the actual difference in temperature retention may be minimal and influenced by other factors, such as the material of the cup and environmental conditions. Ultimately, while color does play a role, it is just one of several factors affecting heat retention.