Answer:
Conduction is usually faster in certain solids and liquids than in gases. Materials that are good conductors of thermal energy are called thermal conductors. Metals are especially good thermal conductors because they have freely moving electrons that can transfer thermal energy quickly and easily.
Heat transfer by convection happens through the air, and there are millions of minuscule air spaces between the fibers. Heat transfer by radiation is also slow since one fiber must radiate its heat to another.
When we give heat then kinetic energy is increase and this heat is transferred from hot metal to cold metal through this free electrons. As in insulator the free electrons are negligible so that the heat is not transferred from hot junction to cold junction due to absence of this free electrons.
Explanation:
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The height of the ball above the ground is 38.45 m
First we will calculate the velocity of the ball when it touch the ground by using first equation of motion
v=u+gt
v=0+9.81×2.8
v=27.468 m/s
now the height of the ground can be calculated by the formula
v=√2gh
27.468=√2×9.81×h
h=38.45 m
In terms of the scientific method, the immediate purpose of doing an experiment is gathering data. You cannot draw conclusions or form a proper hypothesis without some sort of basis and data.
Answer:
(A) -2940 J
(B) 392 J
(C) 212.33 N
Explanation:
mass of bear (m) = 25 kg
height of the pole (h) = 12 m
speed (v) = 5.6 m/s
acceleration due to gravity (g) = 9.8 m/s
(A) change in gravitational potential energy (ΔU) = mg(height at the bottom- height at the top)
height at the bottom = 0
= 25 x 9.8 x (0-12) = -2940 J
(B) kinetic energy of the Bear (KE) =
=
= 392 J
(C) average frictional force = 
- change in KE (ΔKE) = initial KE - final KE
- ΔKE =
-
- when the Bear reaches the bottom of the pole, the final velocity (Vf) is 0, therefore the change in kinetic energy becomes ΔKE =
- 0 = 392 J
\frac{-(ΔKE+ΔU)}{h}[/tex] =
=
= 212.33 N