The work is being done in following cases:
A mover carries a box up a flight of stairs.
A mover carries a box across a room.
Wind blows a pool chair across the yard.
A weightlifter lifts a barbell off the ground.
These are the only cases in which work is being done. The Formula of Work is:
Work= Force applied x Distance moved.
In all of these cases force is being applied and the object on which the force is being applied move in a horizontal or Vertical direction. Thus Work is done !
The collapsed answer of Penchalreddy Badepalli is correct. The composition of two reflections via two mirror making an angle \alpha is equivalent to a single rotation by an angle 2\alpha, hence 2 * 60 deg = 120 deg. And turns is independent of the absolute orientation of the two mirrors in space and/or the direction of incidence of the incoming ray.
One could use elementary geometry to prove this (if you presume the direction of incidence is irrelevant imagine hitting the first mirror at 90 deg, then going retro right back along the normal to the first mirror, and follow the directions).
Iron atoms are heavier than gold atoms
Explanation:
Chart:
Materials Specific heat
Gold 0.129
Iron 0.45
The specific heat of a substance is the amount of heat required to raise the temperature of 1g of the substance by 1K.
We can see that the more the mass of a substance, the higher the specific heat needed to raise the temperature.
Specific heat is directly proportional to the mass of substance.
It also dependent on the amount of heat supplied and the nature of the substance.
- The mass of a body is the amount of substance it contains.
- A heavier substance has more number of atoms in it.
- Since iron has a higher specific it, the atoms must be heavier or more than that of gold.
learn more:
Specific heat brainly.com/question/7210400
#learnwithBrainly
Answer:
P = 3800 W
Explanation:
Power is equal to energy divide by time P = E/t
plug in 4560000 J for energy
convert 20 minutes to seconds
20 * 60 = 1200 seconds
plug in 1200 seconds for time
P = 4560000/1200
P = 3800 W
Most geologists accept radiometric dating techniques as valid because radioactive elements decay at a constant and measurable rate.
Answer: Option C
<u>Explanation:</u>
Scientists prefer radioactive dating to carbon dating because it is more accurate in measuring. The analysis depends upon the radioactive decay of radioactive isotopes of any matter in a given rock or soil.
The parent atoms and daughter atoms are compared while studying, and hence age can be calculated easily. Radioactive decay depends upon the given half-life of the atom, which is a constant and is known. So, it would be very easy to calculate the number of progeny atoms and parent atoms and find out their age.
