Which of these is only a physical change? A. Melting a solid
B. Burning
C. Rusting
D. Forming a precipitate

Ben(55 kg) is standing on very slippery ice when junior(25kg) bumps into him. junior was moving at a speed of 8m/s before the collision and ben and junior embrace after the collision. find the speed of ben and junior as they move across the ice after the collision .

If a substance is in the gas phase, which of qualities of the gas will stay constant? a: volume b: mass c: shape d: position of particles

Two loudspeakers, 5.5 m apart and facing each other, play identical sounds of the same frequency. you stand halfway between them, where there is a maximum of sound intensity. moving from this point toward one of the speakers, you encounter a minimum of sound intensity when you have moved 0.33 m . assume the speed of sound is 340 m/s.part a) what is the frequency of the sound? part b) if the frequency is then increased while you remain 0.21 m from the center, what is the first frequency for which that location will be a maximum of sound intensity? express your answer to two significant figures and include the appropriate units.