The answer is D, hope this helped!
<h2>The frequency of driver is 700 Hz</h2>
Explanation:
The frequency of wave in a string is given by the relation
n = 
here n is the frequency
p is the number of antinodes and l is the length of string .
T is the tension in string and m is the mass per unit length
Thus 420 =
I
Now if there is 5 antinodes , the value of p = 5
Thus n =
II
Dividing II by I , we have
n/420 = 5/3
or n = 5/3 x 420 = 700 Hz
Answer:
the required electrical power when the room air and surroundings are at 30°C.= 52.51822 Watt
Explanation:
Power required to maintain the surface temperature at 150°C from 20°C
P= εσA(T^4-t^4)
P= power in watt
ε= emissivity
A= area of surface
T= 150°C= 423 K
t= 20°C= 303K
/sigma= 5.67×10^{-8} watt/m^2K^4
putting vales we get

P=52.51822 Watt
the required electrical power when the room air and surroundings are at 30°C.= 52.51822 Watt
When the object slides across the rough surface some of its potential energy will be lost to friction.
<h3>Conservation of mechanical energy</h3>
The law of conservation of mechanical energy states that the total mechanical energy of an isolated system is always constant.
M.A = P.E + K.E
When the object slides across the rough surface, some of the potential energy of the object will be converted into kinetic energy while the remaining potential energy will be converted into thermal energy due to frictional force of the rough surface.
P.E = K.E + thermal energy
Learn more about conservation of energy here: brainly.com/question/166559
We use 1/o + 1/i = 1/f where o is the distance of the object, i as distance of the image and f is the focal length.
Substituting, <span>1/ 100 + 1 / i = - 1 /25 </span>
<span>i = - 20 cm </span>
<span>For the case of the problem,</span>
<span>o = (20 + 30) = 50 cm </span>
<span>f = 33.33. </span>Using 1<span> / i + 1 / o = 1/f , </span><span> </span><span>i = 100 cm </span>
<span>M = magnification = - i / o </span>
<span>m1 = -(-20)/100 = 20/100 = 0.2 </span>
<span>m2 = -100/50 = -2 </span>
<span>M = m1*m2 = -2 x 0.2 = -0.4.</span>