Setting reference frame so that the x axis is along the incline and y is perpendicular to the incline
<span>X: mgsin65 - F = mAx </span>
<span>Y: N - mgcos65 = 0 (N is the normal force on the incline) N = mgcos65 (which we knew) </span>
<span>Moment about center of mass: </span>
<span>Fr = Iα </span>
<span>Now Ax = rα </span>
<span>and F = umgcos65 </span>
<span>mgsin65 - umgcos65 = mrα -------------> gsin65 - ugcos65 = rα (this is the X equation m's cancel) </span>
<span>umgcos65(r) = 0.4mr^2(α) -----------> ugcos65(r) = 0.4r(rα) (This is the moment equation m's cancel) </span>
<span>ugcos65(r) = 0.4r(gsin65 - ugcos65) ( moment equation subbing in X equation for rα) </span>
<span>ugcos65 = 0.4(gsin65 - ugcos65) </span>
<span>1.4ugcos65 = 0.4gsin65 </span>
<span>1.4ucos65 = 0.4sin65 </span>
<span>u = 0.4sin65/1.4cos65 </span>
<span>u = 0.613 </span>
Answer:
3 photons
Explanation:
The energy of a photon E can be calculated using this formula:
Where 
corresponds to Plank constant (6.626070x10^-34Js), 
is the speed of light in the vacuum (299792458m/s) and 
is the wavelength of the photon(in this case 800nm).
Tranform the units
The band Gap is 4eV, divide the band gap between the energy of the photon:
Rounding to the next integrer: 3.
Three photons are the minimum to equal or exceed the band gap.
Mars: 0.38
weight = mass x surface gravity
multiplying your weight on Earth by the number above will give you your weight on the surface of Mars
If you weigh 150 pounds (68 kg.) on Earth, you would weigh 57 lbs. (26 kg.) on Mars
Answer:
Option D
490 J
Explanation:
When at a height of 100 am above and released, the ball initially posses only potential energy. When it falls, some potential energy is converted to kinetic energy.
Initial potential energy= mgh where m is the mass, g is the acceleration due to gravity and h is height. Substituting 1 Kg for m, 9.81 for g and 100 m for h then
PE initial = 1*9.81*100= 981 J
At 50 m, PE will be 1*9.81*50=490.5 J
Subtracting PE at 50 m from initial PE we get the energy that has been converted to kinetic energy hence
981-490.5= 490.5 J
Approximately, 490 J
