Pl
how is a pure substance different from a mixture?
a. a pure substance is heterogeneous
b. mixtures cannot be separated by physical means
c. a mixture is made of one substance
d. pure substances cannot be separated by physical means

If this plastic cup is heated to its melting point, what will eventually happen to all the particles in the plastic? a. the particles will begin to move enough that they slide past each other. b. bonds will form and the liquid will become a solid. c. the spaces between the particles will get smaller. d. the particles will change state and become a crystalline solid.

The atoms in a nickel crystal vibrate as harmonic oscillators with an angular frequency of 2.3 × 1013 rad/s. the mass of a nickel atom is 9.75 × 10-26 kg. what is the difference in energy between adjacent vibrational energy levels of nickel? (h = 6.626 × 10-34 j • s, , 1 ev = 1.60 × 10-19 j)

To place a communications satellite into a geosynchronous orbit at an altitude of 22,240 mi above the surface of the earth, the satellite first is released from a space shuttle , which is in a circular orbit at an altitude of 185 mi, and then is propelled by an upper-stage booster to its final altitude. as the satellite passes through a, the booster's motor is fired to insert the satellite into an elliptic transfer orbit. the booster is again fired at b to insert the satellite into a geosynchronous orbit. knowing that the second firing increases the speed of the satellite by 4810ft/s, determine (a.) the speed of the satellite as it approaches b on the elliptic transfer orbit, (b.) the increase in speed resulting from the first firing at a.