Answer:
v (minimum speed) = 2.90 m/sec.

Maximum value of speed will occur at lowest point of vertical circle.
Explanation:
a) What minimum speed is necessary so that there is no tension in the string at the top of the circle but the rock stays in the same circular path?
Using the force balance expression at the top of the circle,
Gravitational Force + Tension force = Centrifugal force

Given that : T = 0
R = length of string = 0.86 m
mass of the spinning rock = 0.75 kg


v (minimum speed) = 2.90 m/sec.
b) what is the maximum speed the rock can have so that the string does not break?
Here the force balance at bottom of circle is represented by the illustration:

Given that:
maximum tension T = 45 N
maximum speed v = ??
mass m = 0.75 kg
∴

c)
At what point in the vertical circle does this maximum value occur?
Maximum value of speed will occur at lowest point of vertical circle.
This is so because at the lowest point; the tension in string will be maximum.
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Answer:
t = 16.5s
Explanation:
Given parameters:
Acceleration = 3.1m/s²
Initial velocity = 0m/s
Final velocity = 51m/s
Unknown:
Time taken = ?
Solution:
To solve this problem we need to reiterate that acceleration is the rate of change of velocity with time.
So;
Acceleration =
v is the final velocity
u is the initial velocity
t is the time taken
So;
3.1 =
3.1t = 51
t = 16.5s
The best represent the size of visible light will be C. Protozoa
The electromagnetic spectrum, gives the overall distribution of electromagnetic radiation by the frequency or wavelength. All EM waves travel at the speed of light in a vacuum, but over a wide range of frequencies, wavelengths, and photon energies.
Visible light wavelengths cover the range of approximately 0.4 to 0.7 μm. electromagnetic spectrum that the human eye can see is the Visible light. Visible light is a form of electromagnetic (EM) radiation, along with radio waves, infrared, ultraviolet, X-rays, and microwaves. the wavelengths that are visible to most human eyes is generally known as Visible light
the best represent the size of visible light is Protozoa, According to the diagram of the electromagnetic spectrum shown,
Learn more about electromagnetic spectrum here brainly.com/question/25847009
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