Why does a rolling sphere slows down?
2 answers:
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Answer:
The distance of the object to the center of the earth increases.
Explanation:
The acceleration due to gravity on Earth is given by:
where
G is the gravitational constant
M is the Earth's mass
r is the distance of the object from the Earth's centre
We notice that:
- g does not depend on the mass of the object
- g is inversely proportional to r
This means that if the distance of the object from the Earth's centre increases, g decreases. So, the correct option is
The distance of the object to the center of the earth increases.
Answer:
d_{b} = 2 d_{a}
Explanation:
The electrical resistance for a cylindrical wire is described by the expression
R = ρ L / A
The area of a circle is
A = π r²
r = d / 2
A = π d²/4
We substitute
R = ρ L 4 /π d²
Let's apply this expression to our case, they indicate that the resistance of wire A is 4 times the resistance of wire B
= 4 R_{b}
We substitute
ρ 4/π ² = 4 (ρ 4/π d_{b}²)
1 / d_{a}² = 4 / d_{b}²
d_{a} = d_{b} / 2