A conservative force F(x) acts on a 2.0 kg particle that moves along an x axis. The potential energy U(x) associated with F(x) is graphed in the figure. When the particle is at x = 2.0 m, its velocity is -1.265 m/s.
What is F(2.)? (sign gives direction)
Between what positions on the left and right does the particle move? Left side?
Right side?
What is the particle's speed at x = 7.0 m
m = 2 kg, x = 2 m , v = - 1.265 m/s
(a) F = - dU/dx
slope of U and x graph gives F
F = U4 - U1/(4-1)
F = -( (-17.4) -(-2.7)/3)
F = 4.9 N , in +x direction
(b) At x = 2 m
U = - 8 J
K = (1/2)mv^2 = 0.5*2*1.265^2 = 1.6 J
E = U +K = - 8 +1.6 = - 6.4 J
This energy is strteched on graph.The range of possible values are between the intersection of E level with U grapph.
range is 1.5 m< x < 13.7 m
(c) at x = 0 m , U = -17 J
K = E -U = - 6.4 - (-17) = 10.6 J
(1/2)mv^2 = 10.6 J
0.5*2*v^2 =10.6
v = 3.26 m/s
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