To solve this problem we will apply the concepts related to wave velocity as a function of the tension and linear mass density. This is

Here
v = Wave speed
T = Tension
= Linear mass density
From this proportion we can realize that the speed of the wave is directly proportional to the square of the tension

Therefore, if there is an increase in tension of 4, the velocity will increase the square root of that proportion
The factor that the wave speed change is 2.
Answer: The area of brick in contact with the floor is 1539
.
Explanation:
Given: Length = 19 cm
Width = 9 cm
Height = 9 cm
As the brick is rectangular in shape. Hence, its area will be calculated as follows.

Substitute the values into above formula as follows.

Thus, we can conclude that area of brick in contact with the floor is 1539
.
I think it is A) but someone might need to double check that.
Answer:
5.1 kg
Explanation:
Its mass on the moon is 5.1 kg because mass is an intrinsic property of a material and does not change with location. Although, its weight might vary because its acceleration of gravity g is dependent on the mass M and radius r of the planet(in this case, moon) involved g = GM/r². Since weight W = mg is dependent o g, weight varies but mass remains constant.
It can't. Waves must have a medium to travel through