Two microphones are places 68 cm apart on the same side of a loudspeaker and collinear with it. The microphones are connected to the two channels of an oscilloscope. For a loudspeaker of frequency 3000Hz the two vibrations observed on the screen of the oscilloscope are in-phase. The frequency is decreased gradually and the vibrations are in phase again for a frequency of 2500Hz. Calculate the speed of sound in air

On vacation in Pensacola a tourist floats lazily in the ocean with 85% of his body below the surface. The density of the ocean water is 1035 kg/m3. What is the tourist average density?

A box rests at a point 2.0m from the axis of a horizontal circular platform. The coefficient of static friction between box and platform is 0.25. As the rate of rotation of the platform is slowly increased from zero, at what angular speed will the box first slide?

If a runner is able to cover 500m in 20 minutes, what was the speed of the runner?