Primary Circular Reactions (1-4 months): This substage involves coordinating sensation and new schemas. For example, a child may suck his or her thumb by accident and then later intentionally repeat the action. These actions are repeated because the infant finds them pleasurable.
We shall consider two properties:
1. Temperature difference
2. Thermal conductivity of the material
Use a cylindrical rod of a given material (say steel) which is insulated around its circumference.
One end of the rod is dipped in a large reservoir of water at 100 deg.C and the other end is dipped in water (with known volume) at 40 deg. C. The cold water if stored in a cylinder which is insulated on all sides. A thermometer reads the temperature of the cold water as a function of time.
This experiment will show that
(a) heat flows from a region of high temperature to a region of lower temperature.
(b) The thermal energy of a body increases when heat is added to it, and its temperature will rise.
(c) The thermal conductivity of water determines how quickly its temperature will rise. If mercury replaces water in the cold cylinder, its temperature will rise at a different rate because its thermal conductivity is different.
Answer:
Power_input = 85.71 [W]
Explanation:
To be able to solve this problem we must first find the work done. Work is defined as the product of force by distance.

where:
W = work [J] (units of Joules)
F = force [N] (units of Newton)
d = distance [m]
We need to bear in mind that the force can be calculated by multiplying the mass by the gravity acceleration.
Now replacing:
![W = (80*10)*3\\W = 2400 [J]](https://tex.z-dn.net/?f=W%20%3D%20%2880%2A10%29%2A3%5C%5CW%20%3D%202400%20%5BJ%5D)
Power is defined as the work done over a certain time. In this way by means of the following formula, we can calculate the required power.

where:
P = power [W] (units of watts)
W = work [J]
t = time = 40 [s]
![P = 2400/40\\P = 60 [W]](https://tex.z-dn.net/?f=P%20%3D%202400%2F40%5C%5CP%20%3D%2060%20%5BW%5D)
The calculated power is the required power. Now as we have the efficiency of the machine, we can calculate the power that is introduced, to be able to do that work.
![Effic=0.7\\Effic=P_{required}/P_{introduced}\\P_{introduced}=60/0.7\\P_{introduced}=85.71[W]](https://tex.z-dn.net/?f=Effic%3D0.7%5C%5CEffic%3DP_%7Brequired%7D%2FP_%7Bintroduced%7D%5C%5CP_%7Bintroduced%7D%3D60%2F0.7%5C%5CP_%7Bintroduced%7D%3D85.71%5BW%5D)
Answer:
C. Quadruple the intensity
Explanation:
The intensity of the sound is proportional to square of amplitude of the sound.
I ∝ A²

When the given sound is twice loud as the initial value, then the new amplitude is twice the former.
A₂ = 2A₁

Thus, to make a given sound seem twice as loud, the musician should Quadruple the intensity