The diagram shows the forces acting on a table tennis ball as it falls. a Copy the diagram and label the force arrows weight and air resistance.
b The two forces are equal but opposite. What is the resultant force acting on the ball?
c Explain why the ball falls at a steady speed.
d What name is given to this steady speed?

  concave means having an outline or surface that curves inward like the interior of a circle or sphere. so the mirror curves inward.

Jenny and fred both play a long note on their trombones. a stationary observer hears the sound increasing and decreasing repeatedly in loudness. which of these must be true? the sound waves from the two trombones have slightly different frequencies.the sound waves from the two trombones have the same frequency.the sound waves from the two trombones have slightly different amplitudes.the sound waves from the two trombones have the same wavelength.the sound waves from the two trombones have slightly different velocities.  lolthe answer is          the sound waves from the two trombones have slightly different frequencies.