A ball of mass 0.35 kg is attached to the end of a horizontal cord and is rotated in a circle
of radius 1.0 m on a frictionless horizontal surface. If the cord breaks when the tension in
it exceeds 80 N, determine:
(a) the maximum speed of the ball,
(b) the minimum period of the ball.
alphonsio
(a) The maximum speed of the ball is approximately 15.11m/s.
(b) The minimum period of the ball is approximately 0.416s.
To solve this problem, we’ll first use the relationship between centripetal force, mass, velocity, and radius. The centripetal force Fc required to keep an object of mass m moving in a circle of radius r with a speed v is given by:
Fc=rmv2
Given:
Mass, m=0.35kg
Radius, r=1.0m
Maximum tension (which is the centripetal force at breaking point), Fc=80N
(a) Maximum Speed of the Ball
We need to determine the maximum speed vmax at which the cord can hold the ball without breaking. Using the centripetal force formula:
v2=mr×Fc
v=mr×Fc
Solving for vmax:
vmax=0.35kg1m×80N
vmax≈228.57
vmax≈15.1185789204m/s
(b) Minimum Period of the Ball
The period T is the time it takes for the ball to make one complete revolution around the circle. The relationship between the speed v, the period T, and the radius r of the circle is given by: