. A sprinter darts from the starting blocks at the sound of the starter's pistol. The position-time graph representing the sprinter's motion during the first few strides would be a straight line. . The force that propels a boat through water is the force that the propeller exerts on the water. . If the supporting cables of an elevator snapped and the elevator began falling, the passengers would become trapped against the ceiling of the elevator provided there is no air resistance or friction in the elevator shaft . When you use the equation E9 = mgh, the only condition on h is that it must be measured in a straight line. . The frequency of the average human voice is below 1000 Hz. . There are some musical instruments that do not need a vibrating source to create sound. . The spreading apart of the colours of light by a prism is called inversion. . Farsightedness can be corrected with diverging lenses. . A Galilean telescope is more useful for studying stars then a reecting telescope