Explanation:
First, we need to determine the distance traveled by the car in the first 30 minutes,
.
Notice that the unit measurement for speed, in this case, is km/hr. Thus, a unit conversion of from minutes into hours is required before proceeding with the calculation, as shown below

Now, it is known that the car traveled 40 km for the first 30 minutes. Hence, the remaining distance,
, in which the driver reduces the speed to 40km/hr is
.
Subsequently, we would also like to know the time taken for the car to reach its destination, denoted by
.
.
Finally, with all the required values at hand, the average speed of the car for the entire trip is calculated as the ratio of the change in distance over the change in time.

Therefore, the average speed of the car is 50 km/hr.
Oxygen. Plants need water sunlight and CO2 to make their food. They get the carbon and the energy from the CO2 and the sun, and they need water as well. Then they release oxygen
Answer: YES
Explanation:
If Tia Ana exposes her eyes to light ray in which it frequency is higher than ultraviolet ray, it may result to a gradual eyes issue such as cataracts as the radiation damages the cornea and the lens in front of the eyes.
Answer:
11.6km
4.4km in the negative direction
Explanation:
Distance is the total length of path covered and traveled by a body.
So, for this car on a straight line;
Total distance = 8km + 3.6km = 11.6km
Displacement is the distance traveled along a path and the direction it takes.
It is a vector quantity with magnitude and directional attributes.
For this journey;
Displacement = 8km - 3.6km = 4.4km in the negative direction.
Answer: 26.6 J
Explanation:
The heat needed to raise the temperature of a solid body, using only a conductive process, has been empirically showed to be equal to the following expression:
Q= c . m. (t2 – t1)
where c= specific heat capacity (in J/gK), m= mass of the solid (in g) ,
and (t2 - t1)= difference between final and initial temperatures.
Replacing by the values, we get:
Q= 0.385 J/gK . 1,550 g. (77.5ºC – 33.0ºC)= 26.6 J