1) Two children are sitting on opposite ends of a uniform seesaw of negligible m
ID: 1544801 • Letter: 1
Question
1) Two children are sitting on opposite ends of a uniform seesaw of negligible mass. If a 39 kg child is 1.9 m from the pivot point (or fulcrum), how far from the pivot point will her 32 kg playmate have to sit on the other side for the seesaw to be in equilibrium?
2)In a circus act, a uniform board (length 3.00 m, mass 22.0 kg ) is suspended from a bungie-type rope at one end, and the other end rests on a concrete pillar. When a clown (mass 67.0 kg ) steps out halfway onto the board, the board tilts so the rope end is 30 from the horizontal and the rope stays vertical. Calculate the force exerted by the rope on the board with the clown on it.
Explanation / Answer
1)
under equilibrium the net torque is zero
T_ net = 0
m_cg (1.9) - m_p g x = 0
39*1.9 = 32 x
x= 2.3 m
(b)
without clown
under equilibrium the net torque is zero
T_ net = 0
(22kg)(9.8ms^2)(1.5m)=3* F_rope
F_rope = 107.8 N.
with clown
(22kg+67)(9.8ms^2)(1.5m)=3* F_rope
F_rope = 436.1 N.
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