If it's a mechanical wave, then its speed depends on the physical characteristics of the medium.
If it's an electromagnetic wave, then its speed depends on the
electrical characteristics of the medium.
Either way, the properties of the medium determine the wave speed.
You want to change the speed ? You have to change the properties
of the medium.
Given that the density of heptane is

The mass of heptane is

The density of water is

The mass of water is

The volume of heptane will be

The volume of water will be

Thus, the volume of heptane is 45.32 mL and the volume of water is 37 mL.
The total volume of liquid in the cylinder will be

The total volume of liquid in the cylinder will be 82.32 mL.
Newton’s first law is motion. For example, an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
Answer:
The maximum speed will be 26.475 m/sec
Explanation:
We have given mass of the toy m = 0.50 kg
radius of the light string r = 1 m
Tension on the string T = 350 N
We have to find the maximum speed without breaking the string
For without breaking the string tension must be equal to the centripetal force
So 
So 

v = 26.475 m /sec
So the maximum speed will be 26.475 m/sec
i believe the answer is 1.5e+6
hope this helps!