The angular position of a point on the rim of a rotating wheel is given by e = 1.70t - 1.71t + 2.77, where e is in radians and t is in seconds. What are the angular velocities at (a) t = 2.47 s and (b) t = 8.39 s? (c) What is the average angular acceleration for the time interval that begins at t = 2.47 s and ends at t = 8.39 s? What are the instantaneous angular accelerations at (d) the beginning and (e) the end of this time interval? (a) Number[43.9 Units rad/s (b) Numbers57.9 Units rad/s (c) Number86.8 UnitsTrad/s^2 (d) Number Units EX (e) Number Units Click if you would like to Show Work for this question: Open Show Work

(a) What is the unit vector in the direction of ? (Express your answer in vector form.) ñ = <

7. YA 60° A = 10.0 30° B 30° 53° D 20.0 37° C = 12.0 10 F = 20.0 B = 5.0

15. The following plot shows the speed v(r) at which stars orbit about the center of a galaxy, as a function of their distance r from the center. v(r) Assuming the galaxy has a spherically symmetric mass distribution, which plot best shows the mass of the galaxy M(r) enclosed within radius r?