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SVETLANKA909090 [29]
3 years ago
13

Given the hypothesis that the element zinc prevents cancer, which of the following procedures BEST exemplifies the nature of sci

entific investigation?
A- Analyze zinc, looking for different forms

B- Do research on zinc and its uses throughout history to determine if there is evidence that zinc prevents incidence of cancer


C- Rely on testimony of friends and relatives, as well as conduct a survey to see if there is a concentration of cancer in the people not taking zinc supplements


D- Give zinc supplements to a group of rats and not to another group. After a period of time, determine if there is a higher incidence of cancer in the control group​
Physics
1 answer:
lidiya [134]3 years ago
4 0

Answer:D

Explanation: i found the answer in an answer key!

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What is the wavelength (in air) of a 13.0 khz vlf radio wave?
bonufazy [111]
Since,
Speed = Frequency * WaveLength

=> WaveLength = Speed / Frequency --- (A)

Frequency = 13.0 kHz.
As the radio waves are electromagnetic waves, their speed is equals to the speed of light. Therefore,
Speed = C = 3 *  10^{8}  m/ s^{2}

Plug in the values in equation(A):

A => WaveLength = \frac{3 * 10^{8}}{13*10^{3}}

Ans: Wavelength = 23.077 kilometers.
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5 0
3 years ago
A ball accelerates from rest down a ramp at 2.4 m/s^2. Write an equation that could be used to determine the balls finals positi
Alik [6]

Answer:

x=2.4t+4.9t^2

Explanation:

This equation is one of the kinematic equations to solve for distance. The original equation is as follows:

X=Xo+Vt+1/2at^2

We know that the ball starts at rest meaning that its initial velocity and position is zero.

X=0+Vt+1/2at^2

Since it is going down the ramp, you can use the acceleration of gravity constant. (9.81 m/s^2) and simplify that with the 1/2.

X=Vt+4.9t^2

Note: Since the positive direction in this problem is down, you are adding the 4.9t^2, but if a question says that the downward direction is negative, you would subtract those values.

Now, substitute in your velocity value.

X=2.4t+4.9t^2

8 0
2 years ago
suppose you want to determine the surface area of this sugar cube. it has edges that are each 2 cm long. if you cut the cube in
ivolga24 [154]

Answer:

Half: 6 cm^2    Whole: 12 cm^2

Explanation:

First, we know that the edges of the cube are 2 cm long. So there are 6 faces on a cube. We do 2x6=12 cm^2 as our total surface area. Then it asks for each half. So you would divide it by 2 and get 6 cm^2 as your half.

5 0
3 years ago
When children use the word “doggie” to refer to every four-legged animal they see, __________ occurs.
Oduvanchick [21]
This is known as overextension! (the correct answer is B.)
7 0
4 years ago
Find the hiker’s gravitational potential energy if the cliff is 60m high
Furkat [3]

Answer:

Potential energy is U=mgh

Explanation:

The potential energy depends on the mass, the acceleration of gravity g and the height at which the object or person is.

Potential energy  U=mgh

In this case we would need to know the exact mass of the hiker in order to calculate the potential energy.

But we know the values of g and h

g=9.81m/s^2

h=60m

So, the potential energy

U=m(9.81m/s^2)(60m)\\\\U=588.6*m

m is the mass of the hiker, wich is not in the description of the problem.

4 0
3 years ago
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