Ultrasound was used to check for cracks in an aeroplane wing. The ultrasound pulse would be reflected from any cracks and from the end of the wing. The diagram shows the oscilloscope trace
produced by the echo. How far along the wing was the crack? The speed of sound in metal is 5000m/s.

Mutt and jeff are running along a path each pushing a cart loaded with rocks. if mutt's wagon has a mass two times greater than jeff's and they want to stay together, arriving at their destination at the same time, what must happen? a) jeff should slow down so mutt can catch up. b) mutt must use half as much force to push his cart. c) mutt must use twice as much force to push his cart. d) mutt and jeff will use the same force, but mutt will take bigger steps.

Complete these sentences. if a roller coaster train has a potential energy of 1,500 j and a kinetic energy of 500 j as it starts to travel downhill, its total energy isj. once the roller coaster train gets closer to the bottom of the hill, its kinetic energy increases to 1,100 j, and its potential energy decreases to j. when the train reaches the bottom of the track and is traveling along the ground, its kinetic energy isj.

Describe how the motion of a spring being pushed forward and backward is similar to the motion of air particles in a sound wave.