Answer:
Rolling friction is much smaller than sliding friction because Rolling friction is considerably less than sliding friction as there is no work done against the body that is rolling by the force of friction. For a body to start rolling a small amount of friction is required at the point where it rests on the other surface, else it would slide instead of roll.
Rolling Friction example: Anything with weels (cars,skateboards) or a ball rooling.
Sliding Friction example: Bicycle brakes,skinning your knee walking,writing.
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.
I'm quite certain the answer is "stress".
Answer:
the volume is 0.253 cm³
Explanation:
The pressure underwater is related with the pressure in the surface through Pascal's law:
P(h)= Po + ρgh
where Po= pressure at a depth h under the surface (we assume = 1atm=101325 Pa) , ρ= density of water ,g= gravity , h= depth at h meters)
replacing values
P(h)= Po + ρgh = 101325 Pa + 1025 Kg/m³ * 9.8 m/s² * 20 m = 302225 Pa
Also assuming that the bubble behaves as an ideal gas
PV=nRT
where
P= absolute pressure, V= gas volume ,n= number of moles of gas, R= ideal gas constant , T= absolute temperature
therefore assuming that the mass of the bubble is the same ( it does not absorb other bubbles, divides into smaller ones or allow significant diffusion over its surface) we have
at the surface) PoVo=nRTo
at the depth h) PV=nRT
dividing both equations
(P/Po)(V/Vo)=(T/To)
or
V=Vo*(Po/P)(T/To) = 0.80 cm³ * (101325 Pa/302225 Pa)*(277K/293K) = 0.253 cm³
V = 0.253 cm³
