To solve this problem it is necessary to apply the concepts of Work. Work is understood as the force applied to travel a determined distance, in this case the height. The force in turn can be expressed by Newton's second law as the ratio between mass and gravity, as well

Where,
m = mass
h = height
g = Gravitational constant
When it ascends to the second floor it has traveled the energy necessary to climb a height, under this logic, until the 4 floor has traveled 3 times the height h of each of the floors therefore

Replacing in our equation we have to

The correct answer is 4.
Answer:

I guess you can round it to 11 seconds.
Explanation:
Going with a speed 9m/s means you are going 9 meters in each second.
If you are going 9 meters in second how many seconds will it take to 100 meters?
Visually;
9 meters - - - 1 second
100 meters - - - ?seconds.
When you write like this 9 times ?seconds equal to 100 meters time 1 second. (you probably know this but just in case)
So to find ?second you multiply 100meters by 1 and divide it by 9 whixh will give you 11.1111 seconds whixh again I believe you can round it to 11.
(Kind of a) Proof;
If 9m * ?sec = 100 m * 1 sec
you send 9 meters to other side.
?sec = (100 m * 1 sec) ÷ 9m
Hope it was clear and it helps! Please let me know if you have any questions.
The kinetic energy of toast is 0.06 J.
<u>Explanation:</u>
Kinetic energy is the way to determine the energy released when an object is in motion. In other times, it can be the energy required to move any object and to make it in motion.
As the mass of the toast is given as 8 g and speed is given as 15 m/s, if we ignore the friction caused by air molecules. Then the kinetic energy is the product of mass and square of velocity.
K.E. =
× mass × v²
Kinetic energy =
Since, the weight is given in grams , it needed to be converted into kg.
Kinetic energy = 0.06 J
Thus, the kinetic energy of toast is 0.06 J.