Answer:
o The result of a chemical change is a different composition; in a physical change, the composition remains the same.
Explanation:
In a chemical change, new kinds of matter are produced although the atoms are the same.
For physical changes, no new kinds of matter formed. Only the state of substances changes.
- Most chemical changes are usually irreversible
- Physical changes are reversible in most parts.
- Changes in state and form are salient characteristics of physical changes.
- When new products are formed from the reactants, it is an indicator of a chemical change.
1. Velocity
2. Time
3. Idk
4. Idk
5. D. I think it may be A. but I think D.
Answer:
Work done, W = 1786.17J
Explanation:
The question says "A 75.0-kg painter climbs a 2.75-m ladder that is leaning against a vertical wall. The ladder makes an angle of 30.0 ° with the wall. How much work (in Joules) does gravity do on the painter? "
Mass of a painter, m = 75 kg
He climbs 2.75-m ladder that is leaning against a vertical wall.
The ladder makes an angle of 30 degrees with the wall.
We need to find the work done by the gravity on the painter.
The angle between the weight of the painter and the displacement is :
θ = 180 - 30
= 150°
The work done by the gravity is given by :

Hence, the required work done is 1786.17 J.
Answer:
0.0321 g
Explanation:
Let helium specific heat 
Assuming no energy is lost in the process, by the law of energy conservation we can state that the 20J work done is from the heat transfer to heat it up from 273K to 393K, which is a difference of ΔT = 393 - 273 = 120 K. We have the following heat transfer equation:

where
is the mass of helium, which we are looking for:

Answer:
A telescope's angular resolution.
Explanation:
Diffraction limit is a minimum angular separation of two sources and it can be distinguished by the telescope. This angle is known as the diffraction limit. It is proportional to the wavelength of light and it has an inverse relation with the diameter of the telescope. Mathematically it is defined as
θ = 1.22λ/d
where θ is the angle, λ wavelength and d is the diameter of the objective mirror (lenz).