Why does the frequency of a siren get higher as an ambulance using that siren gets closer?

1. What is heat? a) A measurement of how fast the molecules of an object are moving. b) The energy contained within an object because of its moving molecules. c) the amount of heat needed to raise the temperature of a substance 1°C 2.

A force of 25 N acts on an object at an angle of 30 degrees above the horizontal. How much work does the force do if the object slides 3 m?

A golf ball is rolling in the grass. What must happen to stop the ball from continuing to roll? An unbalanced net force must be applied. A balanced net force must be applied. The net force must be zero.

What can electromagnetic waves travel through?

Which one does pass through line of wire during electric current flow? electrons or protons?

An element's atomic number is 38. How many protons would an atom of this element have?

What's are some forms of chemical energy

True or false a liquid does not have a definite shape, but it does have a definite volume.

HOw are ferns and trees alike and different and what would survive longer without rain fern or tree

1. Using Pj = e^-BE/Z in the Gibb's form for the entropy, show that F = kb Tln (Z), where F = U - TS is the Helmholtz free energy. Here Z= e^-BE is the canonical partition function ...