4 . A satellite in geosynchronous orbit around Earth has an orbital time period of T , as shown in the
figure. If the mass of the satellite is doubled while keeping the orbital radius (R ) the same, the new
time period of the satellite’s orbit will be
(A) (B)
(C) T
(D)
(E) 2T
Answers
1 . E —Gravity supplies the centripetal force that allows the stars to orbit, which we find by using the
equation:
2 . A —The sprinter only accelerates when changing direction around the curved portions of the tracks
from points A to C and from points D to F.
3 . D —The mass has a centripetal acceleration toward the center of the horizontal circle. Thus, choices
A, B, and C are not correct. The vertical portion of tension must cancel out the gravity force: T cos θ
= mg . Thus, choice E is incorrect. The horizontal portion of tension supplies the centripetal
acceleration toward the center of the circular path: