To solve this problem it is necessary to apply the concepts related to energy conservation.
In this case the kinetic energy is given as

Where,
m = mass
v= Velocity
In the case of heat lost energy (for all 4 wheels) we have to

m = mass
Specific Heat
= Change at temperature
For conservation we have to





Therefore the temperature rises in each of the four brake drums around to 47°C
Answer:
option A
Explanation:
given,
For exerted by the worker = 245 N
angle made with horizontal = 55°
we need to calculate Force which is not used to move the crate = ?
Movement of crate is due to the horizontal component of the force.
Crate will not move due to vertical force acting on the it.



hence, worker's force not used to move the crate is equal to 200.69
The correct answer is option A
Explanation:
Electromagnetic waves are the waves which are created as the result of the electrical waves which are perpendicular to each other and also perpendicular to the direction of propagation.
Electromagnetic spectrum is range of the frequencies and their respective wavelengths of the various type of the electromagnetic radiation.
In order of the increasing frequency and the photon energy and the decreasing wavelength the spectrum are:
radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.
The energy of the radio waves photons is the lowest of all the other waves in the electromagnetic spectrum.
Also, 
Where,
h is Plank's constant having value 
Thus, energy is directly proportional to the frequency. The radio waves have the lowest frequency.
I think the answer is c chemical change
Value of resistor = (12V) /(1.2 x 10^-3A)=10000ohms=10k ohms