Jeff is listening to the radio. He knows that the radio produces sound energy because

A.

he can hear music coming from the radio.

B.

he can feel heat coming from the back of the radio.

C.

he can see the display on the radio when it lights up.

D.

he gets shocked when he touches the radio.

Answer is A.

In 1980, alfa romeo introduced the first system to smooth a rough idle caused by ignition and camshaft timing changes.

If an astronaut takes an object to the moon the following is true (choose only one). a the mass will change but the weight will be the same. b both the mass and the weight of the object will be the same. c the weight will change but the mass will be the same. d both the mass and the weight of the object will change.

Consider a double atwood machine constructed as follows: a mass 4m is suspended from a string that passes over a massless pulley on frictionless bearings. the other end of this string supports a second similar pulley, over which passes a second string supporting a mass of 3m at one end and m at the other. using two suitable generalized coordinates, set up the lagrangian and use the lagrange equations to find the acceleration of the mass 4m when the system is released. explain why the top pulley rotates even though it carries equal weights on each side.