The centripetal force of the rock tied to a string and swung in a circular path is determined as 1.65 N.
The angular speed of the rock is calculated as follows;
ω = 2π N
[tex]\omega = 35^0 \times \frac{2 \pi \ rad}{360^0} \times \frac{100}{3\min} \times \frac{1 \min}{60 \ s} \\\\\omega = 0.339 \ rad/s[/tex]
The centripetal force of the rock is calculated from the product of mass and centripetal acceleration as shown below;
Fc = ma
Fc = m(ω²r)
Fc = mω²r
Fc = 8 x (0.339)² x 1.8
Fc = 1.65 N
Thus, the centripetal force of the rock tied to a string and swung in a circular path is determined as 1.65 N.
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