Answer:
2 times the diameter of the original wire.
Explanation:
Let's call the resistivity of the wire. The original resistance of the wire is given by
where L is the length of the wire and A is the cross-sectional area. Writing the area as
where d is the diameter and d/2 corresponds to the radius, we can rewrite the resistance of the wire as
Which can be rewritten solving for d, the diameter:
Now, we know that the wire must be replaced by a wire with same material (so, same resistivity ), but with 4 times long, which means the new length is . Substituting this into the formula, and keeping in mind that the resistance R must remain the same, we find the new diameter:
so, the diameter must be
2 times the diameter of the original wire.
In the apple-pulling-the orange sequence in this chapter, the force that accelerates the system across the floor is;
Friction between the apple and the floor.
<h3>Frictional Force</h3>
The sequence talked about here is a system showing how an apple was pulling an orange that was located inside a moving toy.
Now, we know that there is usually a force that acts between a moving object and the floor and this force is called friction force.
Thus, the force that makes the apple to pull the orange with acceleration across the floor is called friction force between the apple and the floor.
Read more about Frictional Force at;brainly.com/question/13680415
It’s D. An enlargement (hope this helps!)
Refer to the figure shown below.
W = 217/2 = 108.5 N, the weight of one half of the board.
N = W = 108.5 N, the normal reaction at B or C.
R = frictional force at B or C preventing the board from sliding.
The vertical dashed line through A is a line of symmetry.
By definition,
R = μN = 108.5μ N
where
μ = the static coefficient of friction between the board and the ground.
From geometry,
h = 2a tan(30°) = 1.1547a
Take moments about A for the member AB.
2aN - Rh -Wa = 0
2a(108.5) - 108.5μ(1.1547a) - 108.5 a = 0
217 - 125.285μ - 108.5 = 0
125.285μ = 108.5
μ = 0.866
This is the minimum required static coefficient of friction
Answer: 0.866