Answer:
60 km/hour.
Explanation:
We'll begin by calculating the total distance traveled by the car. This is illustrated below:
Total distance traveled = sum of distance between PQRST
Total distance = 10 + 5 + 10 + 5
Total distance = 30 km
Next, we shall convert 30 mins to hour. This can obtained as follow:
Recall:
60 mins = 1 hour
Therefore,
30 mins = 30/60 = 0.5 hour.
Finally, we shall determine the average speed of the car as follow:
Distance = 30 km
Time = 0.5 hour
Speed =?
Speed = distance /time
Speed = 30/0.5
Speed = 60 km/hour
Therefore, the speed of the car is 60 km/hour.
Answer:
4520 kJ
Explanation:
To make a substance transition phases an energy must be applied, this is know as the latent heat.
Water has a latent heat of 40.7 KJ/mol to turn into vapor.
The molecule of water has a molecular weight of 18. This means that a mol of water weights 18 grams.
With this we can convert the latent heat to use grams instead of mols
Now, the heat needed to vaporize water is simply:
Q = m * DHvap = 2000 g * 2.26 kJ/g = 4520 kJ
Explanation:
Tea cools faster in a cup than in a kettle because when it is on a cup it is more spread out so the cooler air around it is able to cool down each molecule faster than if it were in a kettle which is cooling down slower because the tea is not a spread out
The total energy remains the same, as long as
none of it escapes the closed system.
Answer:
When a bullet is fired from a gun, total momentum before is zero since nothing is moving. After firing the bullet there is a momentum in the forward direction. ... The faster an object is moving or the more mass it has, the more momentum it has in the direction of its motion (momentum = mass velocity).