In a closed system, energy in form of heat (work) can be exchanged but not matter.
The answer to your question is C.
Hope it helped!
All it does is lets him pull in a more convenient direction to raise the load. It has no effect on the required force.
Density is defined as [mass] / [volume] .
The only choice listed with those physical dimensions is 'd' .
The data convincingly show that wave frequency does not affect wave speed. An increase in wave frequency caused a decrease in wavelength while the wave speed remained constant. The last three trials involved the same procedure with a different rope tension.
My guess is A. I'm not 100% positive but i'm pretty sure.
