Answer:
C. her moment of inertia increases and her angular speed decreases
D. her moment of inertia increases and her angular speed decreases
Explanation:
The moment of inertia of a body is the sum of the products of an increment of mass and the square of its distance from the center of rotation. When a spinning person extends her arms, part of her mass increases its distance from the center of rotation, so increases the moment of inertia.
The kinetic energy of a spinning body is jointly proportional to the moment of inertia and the square of the angular speed. Hence an increase in moment of inertia will result in a decrease in angular speed unless there is a change in the rotational kinetic energy.
This effect is used by figure skaters to increase their spin rate by drawing their arms and legs closer to the axis of rotation. Similarly, they can slow the spin by extending arms and legs.
When the person extends her arms, her moment of inertia increases and her angular speed decreases.
_____
<em>Note to those looking for a letter answer</em>
Both choices C and D have identical (correct) wording the way the problem is presented here. You will need to check carefully the wording in any problem you may think is similar.
Answer:
6.75×10^13N
Explanation:
The electric force between the charges can be determined using coulombs law which states that 'the force of attraction between two charges is directly proportional to the product of the charges and inversely proportional to the square of their distance between them.
Mathematically, F = kq1q2/r² where;
q1 and q2 are the charges
r is the distance between the charges
F is the force of attraction
k is the coulombs constant
Given q1 = 5C q2 = 15C r = 10cm = 0.1m k = 9×10^9Nm²/C²
Substituting the given values in the formula we have;
F =9×10^9×5×15/0.1²
F = 6.75×10^11/0.01
F = 6.75×10^13N
Therefore the electric force between them is 6.75×10^13N
I believe the answer is <span>216396.148556 meters per second</span>
Answer:
a: after 1 seconds it will have fallen 0.2452
after 2 seconds it will have fallen 0.981
after 3 seconds it will have fallen 2.2072
after 4 seconds it will have fallen 3.924
Explanation:
the formula for acceleration due to gravity is (ignoring friction I think)
g = G*M/R^2
earths gravitational constant is about 9.807
g = 9.807*M/R^2
The average weight of a brick is 5 pounds and I'm going to say it's 10 feet off the ground.
g = 9.807*5/10^2. g = 0.4905 so every second the brick will go 0.4905 fps faster. (fps means feet per second.)
after 1 seconds it will have fallen 0.2452
after 2 seconds it will have fallen 0.981
after 3 seconds it will have fallen 2.2072
after 4 seconds it will have fallen 3.924
