Question

A 4 kg ball swings in a vertical circle on the end of an 80-cm -long string. The tension in the string is 20 N when its angle from the highest point on the circle is 8 = 30 Part A What is the ball's speed when = 30 °? Express your answer to two significant figures and include the appropriate units. .: A O ? V = Value Units Submit Request Answer Part B What is the magnitude of the ball's acceleration when = 30°? Express your answer to two signihcant figures and include the appropriate units. a Value Units Submit Request Answer

Answer 1

a)

considering equilibrium of forces

mv^2 / r = T + mg cos x

4* v^2 / 0.8 = 20 + 4* 9.8 cos 30

v = 3.3 m/s

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b)

net acceleration is vector sum of tangential and centripetal

a^2 = (v^2/r)^2 + (g sin 30)^2

a^2 = ( 3.3^2 / 0.8)^2 + 4.9^2

a = 14 m/s^2

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c)

x = arctan ( 4.9 / ( 3.3^2 / 0.8))

x = 20