Explain why the bright spectral lines of light emitted from the atoms of an element are unique to that element

To provide some perspective on the dimensions of atomic defects, consider a metal specimen that has a dislocation density of 105 mm-2. Suppose that all the dislocations in 1000 mm3 (1 cm3) were somehow removed and linked end to end.

The net force acting on a 50 kg crate is 0 N. What is the crate's acceleration

In fig. 2-27, a red car and a green car, identical except for the color, move toward each other in adjacent lanes and parallel to an x axis. at time t 0, the red car is at xr 0 and the green car is at xg 220 m.

An electron is to be accelerated from a velocity of 4.50*106 m/s to a velocity of 9.00*106 m/s. Through what potential difference must the electron pass to accomplish this?

Which of the choices is not a statement or direct application of the second law of thermodynamics? There are no 100% efficient heat engines. Heat energy naturally transfers from a high temperature substance to a low temperature substance.

Match these terms with their definitions: 1. unit of electrical resistance ampere 2. unit of electromotive force or electrical potential ohm 3. unit for measuring the strength of an electric current volt 4. unit of electrical power watt

In which is momentum conserved: an elastic collision or an inelastic collision?

List the types of radiation in order from least to most damaging.

Which of the following statements best describes the current state of understanding regarding the apparent acceleration of the expansion of the universe?

Should young people be allowed to do extreme sports? (give me two reasons why) 1. Opinion: 2. Reason why: 3. Reason why: