I): Speed=Distance/Time
=65-30 km/12:30-12:00 hrs
=35 km/00:30hrs
=3500 m/1800 s
=1.94m/s
ii): Average Speed=Total Distance/Total Time
=100000 m/7200 s
=13.88 m/s
iii):No because it has different speeds at
different time intervals
Answer:
4.5 Nm (Anticlockwise)
Explanation:
Let the 75 kg kid is sitting at the left end and the 60 kg kid is sitting on the right end.
Anticlockwise Torque = 75 x 1.5 = 112.5 Nm
clockwise Torque = 60 x 1.8 = 108 Nm
Net torque = Anticlockwise torque - clockwise torque
Net Torque = 112.5 - 108 = 4.5 Nm (Anticlockwise)
Answer:
3.73 * 10^16 photons/sec
Explanation:
power supply = 3.0 V
Emits 440 nm blue light
current in LED = 11 mA
efficiency of LED = 51%
<u>Calculate the number of photons per second the LED will emit </u>
first step : calculate the energy of the Photon
E = hc / λ
=( 6.62 * 10^-34 * 3 * 10^8 ) / 440 * 10^-9
= 0.0451 * 10^-17 J
Next :
Number of Photon =( power supply * efficiency * current ) / energy of photon
= ( 3 * 0.51 * 11 * 10^-3 ) / 0.0451 * 10^-17
= 3.73 * 10^16 photons/sec
If an object is moving with a constant velocity, then by definition it has zero acceleration. So there is no net force acting on the object. The total work done on the object is thus 0 (that's not to say that there isn't work done by individual forces on the object, but the sum is 0 ).
When rubbing two insulators together, electrons from one insulator will be transfered to the other. so the insulator that has just received electrons now has a negative charge as it has received more electrons (making it more negative) the insulator that has just lost electrons has just become positively charged. NEVER SAY THAT PROTONS HAVE BEEN TRANSEFERD.... EVER. ONLY ELECTORNS ARE TRANSFERED.
