Wanda exerts a constant tension force of 12 n on an essentially massless string to keep a tennis ball (m=60g) attached to the end of the string traveling in uniform circular motion above her head at a constant speed of 9.0 m/s. what is the length of the string between her hand and the tennis ball? you may ignore gravity in this problem (assume the motion of the tennis ball and string happen in a purely horizontal plane). a. 22 m
b. 2.5 m
c. 2.2 cm
d. 10 m