Achild whirls a ball in a vertical circle. assuming the speed of the ball is constant (an approximation), when would the tension in the cord connected to the ball be greatest?

a. a little after the bottom of the circle when the ball is climbing.
b. a little before the bottom of the circle when the ball is descending quickly.
c. at the bottom of the circle.
d. nowhere; the cord is stretched the same amount at all points.
e. at the top of the circle.

C. At the bottom of the circle.

Explanation:

Lets take

Radius of the circle = r

Mass = m

Tension = T

Angular speed = ω

The radial acceleration towards = a

a= ω² r

Weight due to gravity = mg

T - m g = m a

T =  m ω² r  + m g

T + m g = m a

T=  m ω² r -m g

From above equation we can say that tension is grater when ball at bottom of the vertical circle.

Therefore the answer is C.

C. At the bottom of the circle.

pythagoras' theorem

square root (-5^2+9^2)

square root (25+81)

square root (106)

angle is tan^-1(9/5)

neg x, pos y