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)
Sound needs medium to travel and it can not travel without medium
so sound wave is a travelling wave
now we also know that sound wave propagate in form of rarefaction and compression.
So all medium particles travel in the direction of wave only
so it is a longitudinal wave also
so correct answer will be
<em>mechanical longitudinal </em>
Data:
h = 2m
m = 45 Kg
PE = ? (Joule)
Adopting, gravity (g) ≈ <span>9,8 m/s²
</span>
Formula:

Solving:



Answer:
<span>
The sled's potential energy is 882 Joules</span>
30grams
Explanation:
If a reaction starts with 30grams then the reaction should end with 30grams.
This in conformity with the law of conservation of mass.
- The law states that "in an isolated system, mass is neither created nor destroyed during chemical transformation".
- Mass is the quantity of matter contained in a substance.
- In chemical reactions, the mass of reactants must always be the same with the mass of the product baring any loss.
- In an isolated system, there is no exchange of energy and mass.
- Chemical systems are usually treated as isolated systems in which mass is conserved.
Learn more:
Chemical laws brainly.com/question/5896850
#learnwithBrainly
C is the correct answer.
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