Answer:
the human body isn't very efficient at converting food into useful work. The human body is less than 5% efficient most of the time. The rest of the energy is converted to heat, which may or may not be useful, depending on how cool or warm a person wants to be.
Explanation:
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
Explanation:
- In chemical reactions, chemical changes occur.
- Atoms are simply rearranged and new bonds are formed.
- Chemical reactions are driven by a need for atoms to attain stability in their structure.
- In all chemical reactions, a reactant or reactants gives new product i.e new substances are formed.
- Most these reactions are not easily reversible.
- They are usually accompanied by the release of energy.
Learn more:
Chemical change brainly.com/question/9388643
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