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kotykmax [81]
3 years ago
14

The data showed that there was no significant difference in healing times between the two groups, so the researcher concluded th

at calcium intake has no effect on bone healing time. Why is the conclusion of the researcher not justified?
Physics
1 answer:
Lana71 [14]3 years ago
3 0

Without knowing the structure and methods of his study,
and the methods of selecting the population sample, we
can't tell whether his conclusion is justified or not.

You might be interested in
A small block with mass 0.0350 kgkg slides in a vertical circle of radius 0.550 mm on the inside of a circular track. During one
Lisa [10]

Answer:

 W_net = μ 5.58,   μ = 0.1     W_net = 0.558 J

Explanation:

The work is defined by the related

          W = F. d ​​= F d cos θ

where bold indicates vectors.

In the case, the work of the friction force on a circular surface is requested.

The expression for the friction force is

              fr = μ N

the friction force opposes the movement, therefore the angle is 180º and the cos 180 = -1

               W = - fr d

the path traveled half the length of the circle

               L = 2 π R

               d = L / 2

               d = π R

we substitute

                 W = - μ N d

Total work is initial to

                W_neto = - μ π R (N_b - N_a)

let's calculate

                W_net = - μ π 0.550 (0.670 - 3.90)

                W_net = μ 5.58

for the complete calculation it is necessary to know the friction coefficient, if we assume that μ = 0.1

                W_net = 0.1 5.58

                W_net = 0.558 J

7 0
3 years ago
A microwave oven operates at 2.50 GHzGHz . What is the wavelength of the radiation produced by this appliance? Express the wavel
sattari [20]

Answer:

The wavelength is \lambda  =  1.2  * 10^8 nm

Explanation:

From the question we are told that

   The frequency of operation of the microwave is  f =  2.50 GHz  =  2.50 *10^{9} \ Hz

     Generally the wavelength is mathematically represented as

          \lambda  =  \frac{c}{f}

Here c is the speed of light with value c =  3.0 *10^{8} \  m/s

So  

         \lambda  =  \frac{3.0 *10^{8}}{  2.50 *10^{9}}

=>       \lambda  =  0.12 \  m

converting to nanometer

           \lambda  =  1.2  * 10^8 nm

6 0
4 years ago
Consider two different rods. The greatest thermal conductivity will be in the rod with:
sergey [27]

Answer:

Options A and D are correct

Explanation:

The thermal conductivity of a metal is the property of a metal to allow heat flow through it. conductivity is higher in conductors and low in insulators. Thermal conductivity is high in metals due to the metallic bonds that exist in metals and the presence of free electrons within the metal which allow easy flow of heat from one atom to another.From the problem the rod which contains freer electrons will allow more heat to flow easily hence have a higher thermal conductivity.

Thermal conductivity has the formula below;

k= \frac{QL}{AΔT}

  • k is thermal conductivity,
  • A is cross sectional area
  • L is length of rod
  • Q is quantity of heat transferred to material.
  • ΔT is temperature change.

From the above equation we can see that thermal conductivity is inversely proportional to A and directly proportional to L. This mean the rod with less area will have a higher thermal conductivity and the rod with a higher length will have higher k. Hence option C i wrong and option D is correct.

For specific heat, its very much different from thermal conductivity. Specific heat is the ability of a material to hold heat while thermal conductivity is the ability of heat to flow through a material.

4 0
3 years ago
A worker pushes horizontally on a 34 kg crate with a force of magnitude 110 n . the coefficient of static friction between the c
Vadim26 [7]
<span>Static frictional force = 126.91 N 
1st worker force = 110 N 
2nd worker = 126.91 – 110 = 16.91 N</span>electron1 <span>· 7 years ago.</span>
4 0
3 years ago
If a frog is the prey what could be the predator ?
bezimeni [28]
The answer is B. Snake.

Hope this helps!
7 0
4 years ago
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