I think it's mass...
The mass of an object refers to the amount of matter that is contained by the object; the weight of an object is the force of gravity acting upon that object. Mass is related to how much stuff is there and weight is related to the pull of the Earth (or any other planet) upon that stuff.
Answer:
D) the bending of a wave as it moves around an obstacle or passes through a narrow opening
Explanation:
Even though light travels in straight line, it will bend around objects if their size is comparative to its wavelength. This phenomenon is called diffraction.
Light will also bend if the light travels from one medium to another medium at an angle, but that is called refraction.
Diffraction occurs in one medium. Refraction occurs when light travels from one medium to another.
The velocity of shortening refers to the speed of the contraction from
the muscle shortening while lifting a load. The relationship between the
resistance and velocity of shortening is inverse. The greater the
resistance, the shorter the velocity of shortening and the smaller the
resistance, the larger the velocity of shortening.
Hopefully this help :)