The variable you can change in an experiment is ( B ) A dependent variable
At the top of the circular motion, both weight and tension provides for centripetal force.
By Newton’s Second Law,
Fnet = ma
mg + T = mv^2/r (since a = v^2/r and weight = mg)
For toy to continue moving in circle at the top,
T > 0
mv^2/r - mg > 0
v >root (gr)
Hence, minimum speed toy must have is 2.80 m/s. Since linear velocity is lower than the minimum linear velocity, the toy will not move in circular motion.
b) Tension at top = mv^2/r - mg
= (0.15)(3.5)^2/0.8 - (0.15)(9.81)
= 0.825 N
Tension at bottom = mv^2/r + mg
= (0.15)(3.5)^2/0.8 + (0.15)(9.81)
= 3.77 N
In the middle, only Tension provides for centripetal force. Hence,
Tension = mv^2/r
= (0.15)(3.5)^2/0.8
= 2.30 N
