Answer:
b) 68,9 km/h a) picture
Explanation:
In this problem, since velocity is expressed in km/h and time in minutes, we have to convert either time to hours or velocity to km/min. It is easier to use hours.
Using this formula we pass time to hours:

Now we can plot speed vs time (image 1). The problem says that the driver uses constant speed, so all lines have to be horizontal.
Using the values of the speed we calculate the distance in each interval

Using these values and the fact that she was having lunch in the third one (therefore stayed in the same position), we plot position vs time, using initial position zero (image 2, distance is in km, not meters).
Finally, we compute the average speed with the distance over time:

Answer:
Repel
Unlike
Atrract
Fur
Balloon
Positivley charged
negative
postive
neutral
Explanation:
It goes from top to bottom
Answer:
1.5 km/s²
Explanation:
Given that:
a car starts from rest; it means the initial velocity (u) = 0 km/hr = 0 m/s
after time (t) = 20 seconds
the final velocity = 108 km/hr = 30 m/s
The acceleration (a) of the car can be determined by using the formula:



a = 1.5 km/s²
Explanation:
Formula for maximum efficiency of a Carnot refrigerator is as follows.
..... (1)
And, formula for maximum efficiency of Carnot refrigerator is as follows.
...... (2)
Now, equating both equations (1) and (2) as follows.
=

= 
= 
= 2.5
Thus, we can conclude that the ratio of heat extracted by the refrigerator ("cooling load") to the heat delivered to the engine ("heating load") is 2.5.