<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>
if a volume of air is warmed it expands due to increased translational kinetic energy as it expands it will start to cool.
<h3>When does temperature increase volume?</h3>
We can then conclude that at constant pressure, temperature and volume are directly proportional: temperature increases, volume increases; decrease temperature, decrease volume.
In this case, the higher the temperature, the greater the kinetic energy that acts on the molecules of this gas, so when the gas expands, these molecules find more space and collide less, which will cause the gas to cool.
See more about volume at brainly.com/question/1578538
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The magnitude is doubled. The direction doesn't change.
S: 198 m
v=39 m/s
u=0
t=?
a=?
v²=u²+2as
(39)²=(0)²+2(a)(198)
1521=396a
1521/396=a
3.84 m/s^2 = a
Hope I helped :)
Answer:
By conservation of energy, it can climb up to a height equal to that it went down before. However, due to the friction in the machines, the total mechanical energy of the roller coaster will decrease. As a result, the first "hill" of many roller coasters are the highest, but the followings will have decreasing heights.
Explanation:
