<h3>It takes 60 seconds to do the work</h3>
<em><u>Solution:</u></em>
Given that,
Force = 100 newtons
Distance = 15 meters
Power = 25 watts
To find: time it takes to do the work
<em><u>Find the work done:</u></em>

<em><u>Find the time taken</u></em>

Thus it takes 60 seconds to do the work
<h3>Answer</h3>
At a high temperature above 20° oxygen solubility starts to decrease.
<h3>Explanation</h3>
Oxygen, O2 is a very essential component of water as we can see in its chemical formula h2O.
The solubility of oxygen decreases as temperature increases. This means that warmer water will have less dissolved oxygen than does cooler water.
<h3>Other factors that affects oxygen solubility in water</h3>
Salt levels
higher the salt levels in water, lower will be oxygen in it.
Pressure
Water at lower altitudes can hold more dissolved oxygen than water at higher altitudes because dissolved oxygen will increase as pressure increases.
Answer:

Explanation:
As we know that moment of force is given as

now we have


now from above formula we have

here we know that

so we have


The only vertical forces are weight and normal force, and they balance since the surface is horizontal. The horizontal forces are the applied force (uppercase F) in the direction the block slides and the frictional force (lowercase f) in the opposite direction.
Apply Newton's 2nd Law in the horizontal direction:
ΣF = ma
F - f = ma
where f = µmg
F - µmg = ma
F = m(a +µg)
F = (20 kg)(1.4 m/s² + 0.28(9.8 m/s²)
F = 83 N