If we increase the speed of rotation of wheel then the sound produced by cardboard touching the spokes of the wheel will become
a) shrill (b) grave (c) remains the same

An airplane flies eastward and always accelerates at a constant rate. at one position along its path it has a velocity of 34.3 m/s, it then flies a further distance of 40100 m and afterwards its velocity is 47.5 m/s. find the airplane\'s acceleration and calculate how much time elapses while the airplane covers those 40100 m.

If frequency goes down, what happens to wavelength? does it get shorter or longer?

In the cores of extremely hot red giants, nuclear reactions convert helium to