[填空题]
A hammer thrower accelerates the hamme)vzk q+j + cja;gcm1q-r from rest within four full turns (revix-jc5.kmhg.meo2 n(ei gl 9+olutions) and releases it at a speed+ec-2 mmii5ge9hlo g.(n x.jk of 28 $m/s$ Assuming a uniform rate of increase in angular velocity and a horizontal circular path of radius 1.20 m, calculate (a) the angular acceleration, $rad/s^2$ (b) the (linear) tangential acceleration, $m/s^2$ (c) the centripetal acceleration just before release, $m/s^2$ (d) the net force being exerted on the hammer by the athlete just before release, N (e) the angle of this force with respect to the radius of the circular motion. $^{\circ} $