Final answer:
To make a 0.144 kg ball revolve in a horizontal circle with a radius of 0.624 m and a speed of 3.22 m/s, a person must exert a centripetal force of approximately 2.38 Newtons on the string.
Step-by-step explanation:
To determine the force a person must exert on a string to make a ball revolve in a horizontal circle with a given radius and speed, we must find the centripetal force required for circular motion. The centripetal force (Fc) necessary to maintain the ball in circular motion is given by the formula:
Fc = m*v2/r
Where m is the mass of the ball, v is the tangential speed, and r is the radius of the circle. Plugging in the values given:
Fc = 0.144 kg * (3.22 m/s)2 / 0.624 m
Calculating this, we find:
Fc ≈ 2.38 N
Therefore, the person must exert a force of approximately 2.38 Newtons on the string.