题目3单选题
A conical pendulum composed of a massless rope (length L) and a bob (mass m) is shown in Figure. How much is the period for the pendulum? <img src="https://tihai-oss-cloud.itihey.com/img/cbe8587bb6d92d5b4a8e3eac8429760e.png">A. <img src="https://tihai-oss-cloud.itihey.com/img/0be7dce1b91779b467ccbd8fc2e25bd9.png">B. <img src="https://tihai-oss-cloud.itihey.com/img/62973bf50b92d924f8ce8a0aae16d4d4.png">C. <img src="https://tihai-oss-cloud.itihey.com/img/69c57944ba8f3a4e7a71333e03f037be.png">D. <img src="https://tihai-oss-cloud.itihey.com/img/09a8449ab755f272aa481badb8eebc3a.png">