<u>Answer:</u>
<em>The average speed of the car is 66.9 km/h</em>
<u>Explanation:</u>
Here distance covered with the speed <em>57 km/h=7 km </em>
distance covered with the speed of <em>81 km/h=7 km</em>
<em>Average speed is equal to the ratio of total distance to the total time.
</em>
<em>total distance= 7 + 7= 14 km </em>
<em>
</em>
<em>time taken to cover the first 7 km= 7/57 h </em>
<em>time taken to cover the second part of the journey = 7/81 h
</em>
<em>average speed = 
</em>
<u><em>Shortcut:
</em></u>
<em>When equal distances are covered with different speeds average speed=2 ab/(a+b) where a and b are the variable speeds in the phases.
</em>
Answer:
Ceiling fan
Explanation:
Ceiling fan is a perfect and typical example of electrical energy being converted to mechanical energy.
In most systems, energy is usually transformed from one form to another. Energy is not created neither is it destroyed. We know this by virtue of law of conservation of energy.
- The ceiling fan is powered by electrical energy from an outlet.
- The energy from the outlet is used to drive the blades of the fan and set them into motion.
- This is mechanical energy.
Answer:
The capillary rise of the glycerin is most nearly 
Explanation:
From the question we are told that
The diameter of the glass tube is 
The density of glycerin is 
The surface tension of the glycerin is 
The capillary rise of the glycerin is mathematically represented as
substituting value
Therefore the height of the glass tube the glycerin was able to cover is
