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A 0.420 kg pendulum bob passes throughthe lowest part of its path at a speed of

ID: 1723077 • Letter: A

Question

A 0.420 kg pendulum bob passes throughthe lowest part of its path at a speed of 3.30 m/s. (a) What is the tension in the pendulum cableat this point if the pendulum is 80.0 cm long?
1 N

(b) When the pendulum reaches its highest point, what angle doesthe cable make with the vertical?


(c) What is the tension in the pendulum cable when the pendulumreaches its highest point?
3 N (a) What is the tension in the pendulum cableat this point if the pendulum is 80.0 cm long?
1 N

(b) When the pendulum reaches its highest point, what angle doesthe cable make with the vertical?


(c) What is the tension in the pendulum cable when the pendulumreaches its highest point?
3 N

Explanation / Answer


(a)
   from the given problem we casn see that at thelowest point on the path the net upward force is
    Fup = T - m g
            = m (vt2 / r)
   so the tension will be
   T = m [g + (vt2/ r)]
      = ......... N
(b)
   according to the conservation of mechanicalenergy we get that
   (KE + PEg)f = (KE +PEg)i
   so as the bobgoes from the lowest to the highest pointwe get that
   0 + m g [L (1 - cosmax)] = (1 /2) m vi2 + 0
   cosmax = 1 -(vi2 / 2 g L)
   max = ..........o
(c)
   at the highest point on the path the bob is is atrest and the net radial force will be
    Fr = T - m gcosmax
          = m(vt2 / r)
          = 0
   T = m g cosmax
      = ........ N