Answer: conduction.
Explanation:
1) A skillet or pan will be in direct contact with the food.
2) Being the skillet a solid matter, it transfers heat by conduction.
3) There are three heat transfer mechanisms: convection, conduction, radiation.
i) Convection: only happens in fluids: liquids and gases.
It is a slow mechanism and is due to the motion of the particles of fluid.
This is not the case, since the skillet is solid and the eggs are in direct contact with it. If the eggs were separated from the skillet convection might happen but it would be very slow and the eggs would take so long time to be cooked.
ii) Conduction: happens by direct contact among neighboring particles, due to their vibrations. The vibrations are only transmitted to neighboring particles, which is only possibble when they are in direct contact, so it is the classical mechanism in solids. So, the heat transfer using the skillet to cook scrambles eggs is an example of conduction.
iii) Radiation: is the transfer of heat by infrared waves. It is an important mechanism when the substances are separated by vaccum or gases and the difference of temperature is high. Yet, this is not the importante mechanism here. You feel heat radiation when you put your hand close to the skillet.
Answer:
1920Joules
Explanation:
The formula for calculating the kinetic energy of a body is expressed as;
KE = 1/2 mv²
m isthe mass
V is the speed
For the two masses, the combined KE is expressed as;
KE = 1/2(m1+m2)v²
KE = 1/2(45+15)(8)²
KE = 1/2 * 60 * 64
KE = 30 * 64
KE = 1920J
Hence the combined kinetic energy of the boy and the bicycle is 1920Joules
De Broglie's identity gives the relationship between the momentum and the wavelength of a particle:
where
p is the particle momentum
m is its mass
v its velocity
h is the Planck constant
is the wavelength
By re-arranging the equation, we get
and by using the data about the proton, given in the text, we can find the proton's wavelength:
An example of an aerobic activity would be A, Cross-country skiing
Answer:
4.17 m/s²
Explanation:
We are told the reaction time is 0.2 s. Now, during this reaction time the car is going to travel an additional distance of
: x = u × t = 40 × 0.2 = 8 m
where u is the initial velocity of the car which is 40.0 m/s.
We are told that he had 200 m to stop before applying brakes. Thus, after applying brakes, he now has a distance to cover of; s = 200 - 8 = 192 m
Since vehicle is coming to rest acceleration would be negative, thus using Newton's equation of motion, we have;
v
² = u² - 2as
v = 0 m/s since it's coming to rest
u = 40 m/s
s = 192 m
Thus;
0² = 40² - 2(a)(192)
0² = 1600 - 384a
a = 1600/384
a = 4.17 m/s²
