A small difference between means may not be statistically significant, but it could reach statistical significance with a large
1 answer:
Answer:
Increasing the sample size could make a small difference between means reach statistical significance because;
a) As N increases the standard error gets smaller reflecting less variability in sample means, which allows greater sensitivity to detect small but significant differences
Explanation:
The p-value of a test statistic is used to express the level of significance of the test result. A significant result is typically considered as one with a small p-value of less than or equal to 0.05 at which point we reject the null hypothesis
The p-value can be made smaller by either
1) Increasing the size of the sample (N)
2) Decreasing the standard error
3) Increasing the difference between the hypothesized parameter and the statistic of the sample
The standard error, SE, is given as follows;
Where;
σ = The standard deviation of the sample
n = The sample size
Therefore the standard error decreases, gets smaller, with increasing sample size, N
Therefore, the small difference between the sample mean could reach statistical significance with a large sample because as N increases the standard error gets smaller reflecting less variability in sample means, which allows greater sensitivity to detect small but significant differences.
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Answer:
a. The station is rotating at
b. the rotation needed is
Explanation:
We know that the centripetal acceleration is
where is the rotational speed and r is the radius. As the centripetal acceleration is feel like an centrifugal acceleration in the rotating frame of reference (be careful, as the rotating frame of reference is <u>NOT INERTIAL,</u> the centrifugal force is a fictitious force, the real force is the centripetal).
The rotational speed is :
Knowing that there are in a revolution and 60 seconds in a minute.
The rotational speed needed is :
Knowing that there are in a revolution and 60 seconds in a minute.
<h2>Answer:</h2>
Torque = <em>2.05 x 10²⁸ Nm</em>
Energy = <em>3.54 x 10³³ J</em>
Average power = <em>1.02 x 10²⁸ W</em>
<h2>Explanation:</h2>(a) Torque (τ) is the rotational effect of a given force.
It is given by
τ = I x α -------------(i)
Where;
I = rotational inertia of the object
α = angular acceleration of the object.
In this case, the object is the Earth. Therefore,
I = 9.71 x 10³⁷ kg m²
α = ω / t
Where;
ω = angular velocity of earth = 2π rad / day
<em>Since </em>
<em>1 day = 24 hours and 1 hour = 3600seconds</em>
<em>1 day = 24 x 3600 seconds = 86400seconds</em>
<em>=> ω = 2π rad / 86400seconds</em>
<em>=> ω = 7.29 × 10⁻⁵ rad/s</em>
<em />
t = 4 days = 4 x 24 x 3600 seconds = 345600 seconds
=> α = ω / t
=> α = 7.29 × 10⁻⁵ / 345600
=> α = (7.29 × 10⁻⁵) / (3.456 x 10⁵)
=> α = (7.29 × 10⁻⁵⁻⁵) / (3.456)
=> α = (7.29 × 10⁻¹⁰) / (3.456)
=> α = 2.11 × 10⁻¹⁰ rad/s²
Now substitute the values of I and α into equation (i)
τ = 9.71 x 10³⁷ x 2.11 × 10⁻¹⁰
τ = 9.71 x 10²⁷ x 2.11
τ = 20.5 x 10²⁷ Nm
τ = 2.05 x 10²⁸ Nm
(ii) The energy (rotational energy) E is given by;
E = x I x ω
E = x 9.71 x 10³⁷ x 7.29 × 10⁻⁵
E = 35.4 x 10³² J
E = 3.54 x 10³³ J
(iii) The average power P, is given by;
P = E / t
P = 3.54 x 10³³ / 345600
P = 1.02 x 10²⁸ W