<h3><u>Answer;</u></h3>
= 75 %
<h3><u>Explanation</u>;</h3>
To measure efficiency of a machine, compare the work output to work input.
Efficiency = Work output/ work output × 100 %
= 300/400 × 100
= 75 %
Answer:
Average power output of athlete = 11025 Watts
Explanation:
Work done is defined as the product of force applied and the displacement perpendicular to the force.
Work = 
Power is defined as work done per unit time.
Power = 
Here the person lifts 900 kg.
Height = 2.5 m
Time interval = 2 seconds
Force = 
= 
= 8820 N
Work done =
= 
= 22050 J
Power = 
= 11025 Watt
This is weird.
All three 'choices' are true.
Line um up. (a) shows how to solve the problem. (b) does it. and (c) is the answer.
Answer
• Improving the environmental performances
• Developing Green Mining technology
Explanation
The effect to the environment caused by opal mining are; impact on soils and geology, clearing of native vegetation disrupting flora and fauna, change in land use and effects of air quality.
Opal mining is currently examining environmental impacts and adopting measures that mitigate the impacts making the process less destructive to the environment.
With the current commitment to sustainability, opal companies are investing funds for Green Mining as a positive way to impact the environment before and after mining.
The answer to this is A. this is because, refraction with a light or sound wave changing its direction involve propagation,(in which propagation is the change in direction of a light or sound wave)
