Legend has it that an apple falling on Isaac Newton’s head in the 17th century urged him to define the laws of gravity. Ignoring the effects of air resistance, objects falling to Earth accelerate at a rate of 9.8m/s^2. So Newton probably copped a fair knock to the old noggin.
But what if Newton was sitting under an apple tree on another planet? Would the apple have hit him at a higher or lower speed? This app to allows you to visualize the rate of acceleration on other planets with augmented reality!