.1 a) What is black body and black body radiation? Write down the Plank’s Postulates and derive Plank’s energy density formula? Show that the Plank’s energy density is

formula valid for all types of wave length.

b) The effective surface temperature of the Sun is 5800K at what wave length

would you expect the Sun to radiate most strongly? (Wien’s constant = 2.898 x 10-3 m. K)​

b. lifting dumbbell weight at 20-degree angle from the body after a 45-degree angle

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.