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11. Young David who slew Goliath experimented with slings beforetackling the gia

ID: 1722523 • Letter: 1

Question

11. Young David who slew Goliath experimented with slings beforetackling the giant. He found that he could revolve a sling oflength 0.600 m at the rate of9.00 rev/s. If he increased the lengthto 0.900 m, he could revolve the slingonly 7.00 times per second.

(a) What is the speed of the stone for eachrate of rotation?
1 m/s at 9.00 rev/s
2 m/s at 7.00 rev/s

(b) What is the centripetal acceleration of the stone at9.00 rev/s?
3 m/s2

(c) What is the centripetal acceleration at 7.00 rev/s?
4m/s2 (a) What is the speed of the stone for eachrate of rotation?
1 m/s at 9.00 rev/s
2 m/s at 7.00 rev/s

(b) What is the centripetal acceleration of the stone at9.00 rev/s?
3 m/s2

(c) What is the centripetal acceleration at 7.00 rev/s?
4m/s2

Explanation / Answer

(a) What is the speed of the stone for eachrate of rotation?
1 m/s at 9.00 rev/s
v=rw=0.6*2*3.14*9/1=33.912m/sec


2 m/s at 7.00 rev/s
v=rw=0.9*2*3.14*7/1=39.564m/sec



(b) What is the centripetal acceleration of the stone at9.00 rev/s?
3 m/s2
v*v/r=33.912*33.912/0.6=1916.70624m/sec2


(c) What is the centripetal acceleration at 7.00 rev/s?
4 m/s2

v*v/r=39.564*39.564/0.9=1739.23344 m/sec2